Hmmmm..... I've seen it in Smiths, possibly. There is a selection of travel books there but to be honest it covers every destination and the section was not that big, so I'm not sure I would leave it until Gatwick and then be disappointed.
My local Waterstones sells it but they have a great travel section. I've also seen it in Ottakers if you don't fancy buying online which is what I always do
The reason i wanted to buy it at Gatwick is that the new edition comes out on the 29th August and we leave for Gatwick on the 31st so It would be easier to pick it up at Gatwick but maybe i should just try go out and get it before we leave. Thanks for your help.