Surely the biggest headache for the British Navy will be that to maintain " an agile, well-defended carrier task group" they're going to have to concentrate a very large portion of the whole fighting fleet around each carrier - or depend on other nations to help out.
This may well work in Small Wars but if it comes to peer-to-peer or even near-per conflicts it may be impossible to get the assistance from your friends as they will have their own interests to look after