Yeah finding a suitable place to rough shoot is a real pain!
This is the first I've heard about paying to rough shoot somewhere though...
Luckily two lads I went to school with live on farms, so through a bit of negotiation with their dads/grandads we got full permission to shoot over the farms. We have actively tried to expand the areas which we shoot over by asking round the neighbouring farms, but as previously mentioned, these farms are 'as tight as a duck's arse' when it comes to rough shooters such as us.

I can only suggest that you do a bit of digging amongst family/friends, to see if they have an uncle/family member/etc who owns/works on a farm.

If you just want to do air rifle shooting then you shouldn't have a big problem as long as you seem polite, and not a little scally - it's when firearms become involved that they really start turning their noses up...