Almost any UK civilian airport is eqipped and able to handle any military flight, including return trips from Afghanistan, whether you are in uniform, civvies or dressed as clowns.
Generally you will be welcomed and almost certainly given preferential treatment because of the respect the vasy majority of us have for the contribution the armed forces
have always made, not just now.
What we don't tolerate is the attitudes Seldomfitforpurpose and his petty minded idiots who fail to appreciate that all costs of every flight into a UK civilian airport do not differ from any other, in fact it's cheaper to operate such flights into civilian airports than any military base - the MOD charges more than anyone else in the UK.
It's a charter flight and costs are the same as charged any where else, do you expect them to be free
?