I've been there and tried that and the problem in and around oxford is the designations on all of the decent woodlands, like sssi and ancient woodlands etc, I searched for quite a few months and I couldn't find anything within a low commutable distance from the city its self.
I'm not saying it doesn't exist though but with Oxford being such a historic city all of the woodlands around it are protected.
Use this website and see for yourself
www.magic.gov.uk click on interactive map and enter the city name, you will need to bear in mind that no planning will be granted if there are protected animals or flowers in the woodlands like badgers, doormice etc so you will need to have surveys of the site done BEFORE you even set foot on the land and a typical phase 1+2 ecological survey will set you back 5k+.
and please bear in mind you can be prosecuted now even if you accidentally disturb a badgers set,
As for site set up costs you need to start working on £200 per player for the equipment costs ie 40 player site £8k and then building the site you obviously have to pay for the materials and the labour and don't forget the longer it takes you to build your site the more money you will have to pay in land rent.
But there a many costs that you might overlook like where will you store all of your eqipment? in a container or in a lockup? more costs..
