"I need a wee!"

We jumped out of the car, fumbled with seatbelts, written instructions, combination safes by the gas meter. I punched in the code and the keys fell out onto the mat.

"Oh lord, there are three of them. Which one is it?"
"Silver for exterior. The Yale is the inner lock."
"Hurry! He's hopping!"

Metal scraped by the tumblers and the door swung open. We fell through the entry into the porch, Samuel pushing eagerly, anxious to be first. "Inside!" said Emily. "Oh look, there's a toilet here. Right Will, quick!"

"Actually," said Will, "I don't need a wee."

And that was the introduction to our holiday cottage.

When it comes to parenting, you wonder why on earth you thought doing something that's gone so horribly wrong was ever a good idea - the meal out, the church service, the camping trip. I recall being at a festival where we'd arrived late in the evening, hastily erected tents, reconfigured the seats in the van for sleeping purposes (which turned out to be a mistake) and hauled out all manner of holdalls and cooking apparatus, all the while trying to control the boys, fractious and ill-tempered after a two hour journey.

Let's deal with the elephant in the room here: a lot of the time, family holidays are no fun at all.Oh, the suntans and photos tell a different story, and when it comes to the formation of memories, both have a glorious whitewashing effect. The car fights, the incident at the zoo that you're not allowed to discuss under the terms of the super-injunction, the moments when you're in the kids' bedrooms for the seventeenth time in as many minutes because IT'S HALF PAST BLOODY ELEVEN - all gone in a heartbeat under the recollection of clear skies, glorious sunsets and crashing surf.

The inconvenient truth is that you do not take a holiday to get any sort of rest: that is the purpose of a child-free minibreak, and if you are fortunate enough to have in-laws with the capacity to look after the kids that's brilliant. Now that we've established this, let's get some other facts straight: family holidays, traumatic as they may be, are a good thing. No one said that parenting had to be fun all the time. It's the toughest thing you'll ever have to do, and getting to the end of a fortnight's holiday with three bickering primary school children with your sanity intact is the ultimate test of just about anyone's mettle. It's the childcare equivalent of Wrestlemania or The World's Strongest Man. If I'm not exactly selling this to you, bear in mind that the alternative to taking a holiday is cabin fever, which is worse.

For many children a change is as good as a rest, but when it comes to ASD there are all sorts of clichés - some with merit, some well-worn and irritating. The arrival in an unfamiliar, alien environment (and the anticipated fallout) is one of them. The absence of routine is another. "What are you going to do," asks the well-meaning friend or relative, "when it gets to five o'clock and they can't watch Charlie & Lola?"

I'm sure that for some people this sort of alarmism is well-founded. Two of my children can't sleep without the iPod, so we have learned to take it with us, and have got through a number of docking stations along the way. I have ransacked cabinets, uprooted small trees and discovered new and uncatalogued forms of life under the bed in my quest to find the stuffed Care Bear that Samuel has not had for days but which he absolutely and positively has to take with him. You will know yourself how susceptible your child is to change, and you'll know how much room there is in the boot of the car for familiar toys, tablets and trinkets. While we're on that subject, may I advise you - above all else - to start packing at least three days in advance of any holiday you're taking? Do not do what we did and leave it until the night before a planned five a.m. start to do the lion's share, frantically fixing roof boxes to the top of the Renault in the fading of light and the fraying of tempers, cramming the camping gear into the trailer and then discovering that it was the Olympic Opening Ceremony and we couldn't really miss that, could we, seeing as it was a one off and they had Mister Bean?

Our family has coped with the inevitability of unanticipated difficulty by tempering it with the familiar. We've been to Butlins several times (the Family Fund has helped with this more than once, and while I don't want to make a big thing about it I ought to use this opportunity to publicly thank them) and we visit the same patch of Welsh coast every summer. Butlins can be noisy but there is enough familiarity for Samuel to be comfortable, with enough to distract him if things go wrong. It is well-fitted, like a tailored suit: only for special occasions, but reliable.

When we're camping - typically in the company of extended family - it's the same, but different. On a given day we can pick one of four or five activities, weather permitting, and the children know what will happen and where. We know where to shop if we run out of nappies, what time the ice cream parlour closes, the best spots for laundry. We've seen it and done it all before, and thus the beach, where Samuel is happiest, becomes the default option.

Besides, something happened on those beaches that I chose to write down, because I knew I'd need it one day. It was 2012 - the year of the Olympics. Samuel had just received his diagnosis (it would be a further three and a half years before we told him) and we'd made the first, tentative steps towards understanding the way he ticked. It had been a long and difficult year, but when we arrived in Pembrokeshire that summer, he was like a puppy off its leash, darting to and fro across the sand, stopping to feel it run through his fingers, occasionally throwing it in the direction of the ocean despite my admonishments. He climbed across rocks with a heretofore unseen speed and dexterity that astounded me. He would find pieces of driftwood and use them to carve his name. Most of all, there was the sea itself. He would run to the water's edge and paddle, and then dart back from the incoming tide, gloriously happy.

Not that walking on the beach doesn't carry its own hazards, as we found out the year we lost three children at once. It happened one afternoon we'd taken the boys down while we waited for the others, and then I'd returned to the car to fetch more bags and wandered back across the road to find the rest of the extended family venturing northwest towards the cove. Emily and I strode off in pursuit: she tackled the shingle, while I padded along the sand below. It wasn't until we reached the mouth of the river that I realised something was wrong.

I shouted up to her, my words apparently hard to decipher in the afternoon breeze. "Where are the children?"

We assumed that they'd gone on ahead with the others, but I'd glanced from one group to another and another and could see no sign of any of them. I turned round: they were halfway up the beach, standing very sensibly in the same spot we'd left them. I abandoned the bags I was carrying, and we hurried back.

Stephen and Will were visibly upset, although the tears didn't last long. Only Samuel was completely calm. "Weren't you worried?" Emily asked him. "Weren't you worried when you found you'd been left on your own on the beach?"
"No," came the response.
"Good boy," she said. "Is that because you knew Mummy and Daddy would come back to get you?"
"No," he said. "It's just I don't really like being supervised."

James is a freelance writer who has written about autism for years. His parenting blog is currently invite-only, but he produces occasional articles for Metro and blogs about Doctor Who at Brian of Morbius. He and his wife have four sons, two on the autistic spectrum.