What you are describing is basically the result of GA in Europe being privatised and not subsidised by the general taxpayer as a transport infrastructure which is what the USA does.
There isn't anything one can do about it, but yes it is crap.
However this
Took a Citation into Norwich for a few hours last week. The aircraft owner got a bill for about £400 to land and be handled there and thats not a major airport. It does make you wonder how anyone can afford to fly in the UK or for that matter how the airports and their sub industries can manage to survive over here.
is wholly self inflicted by the owners of these planes, most of whom couldn't care less what they pay, and this has given rise to silly prices like that. Add to that inept airport management (pretty well the standard in much of Europe) which "likes jets and doesn't like pistons" and you get all the airports which have priced GA out while happily charging £400 a pop to jet owners who pay it without a blink.
IMHO, if jet owners decided to become strategic on this, we would see big changes at airports, which would probably consider killing the "mandatory handling" system which has become so common. But this will never happen all the time enough people want to pay £5000 for a spot of shopping at Cannes.
Cranfield's charges are plain silly; they have decided that the schools there make them enough money and they don't want anybody else going there.