The Land Registration Act 2002 changed things in respect of land which is registered on the Land Register. ('Land', as far as the relevant laws are concerned, includes any buildings standing on that land).
Your first course of action should be to search the Land Registry records to find out if the land is registered. Assuming that it is, the title plan and title register will cost you �3 each:
http://www.landregisteronline.gov.uk/
If you find that the land is unregistered, simply squatting in the property for 12 years may well give the right to claim the title to the land, because the old rules will still apply.
If the land is registered, you will only need to squat on the land for 10 years before you can apply to have the title transferred to you. However, unlike the automatic process under the 12 year rule for unregistered land, the registered title holder has the right to oppose your application for the transfer of the title. (Any valid opposition would mean that your claim would automatically fail). See here:
http://www1.landregistry.gov.uk/assets/library /documents/lrpg004.pdf
Chris