1990s Children's/YA Book boy left in France - cave

I read a book at some point in the 1990s and would love to read it again, but can't seem to find it on google. It's a young adult book about a boy who goes on holiday to France with his parents, but they're arguing a lot and his mum is really stressed because she has to drive around the Peripherique. His parents are in two cars as they have lots of luggage and a few children (I think), and the boy accidentally gets left behind (like in Home Alone), but no-one notices as they leave in separate cars. He has to fend for himself and shelters in a cave. I remember that at one point he has some wet matches, and he gets food by building a dam to catch fish and stealing eggs from a farm.

I think it was by a British author but it may not have been - any ideas would be most appreciated (maybe my googling skills aren't good enough!)

I've found it! It's called Hiding Out by Elizabeth Laird if anyone's interested.

Touchstone fairy: Hiding Out.

I tried to search for this for you with no luck, glad you found it!