If you are travelling via London, make sure you don't have to change between Airports, (Heathrow to Gatwick), or between terminals in Heathrow itself, especially between T5 and T3 due to T5's chronic delays. Changing between Heathrow to Gatwick is EXPENSIVE if the carriers do not provide free and PUNCTUAL and RELIABLE transport.

Also, I have heard horror stories of ppl transferring / changing flights at a UK airport and with enhanced security checks. ONE HAND CARRY limit and ALL LIQUIDS less than 100 ml in hand carry.

Also, IPhone might not be a very clever thing to take there unless it is already unlocked and tested on other networks.

_x