With the holiday season coming up, this book Travelling Abroad With Children looks useful. It's currently available for only 2.99gbp from the Book People. I haven't read it so can't vouch for it but at that price, even with P&P it's pretty cheap. Of course, you could always buy lots of childrens books to keep them amused and your own summer reading, at the same time! (I don't work for them, honest!!)