Just to add to the good advice given so far it is important that you make sure you arrange a departure back to the UK through foreign customs as well. On my relatively recent trip down to Menorca I cleared customs on the outbound leg with no problem (24hrs notice to Tours which actually only require 4hrs), however on my return trip to the UK the customs officer pointed out on no uncertain terms that I should have given notice of my intended departure time and airport back to the UK.
