I take it there is a formal lease for the house (i.e. the part you pay �12 a year for). If there is not, your solicitor has been negligent and you need to get it sorted out.
As far as the land is concerned (the �2 part) it looks as if you may have just a licence, not a lease. If so, the land owner can probably terminate it at any time on reasonable notice. Your solicitor should have explained the position to you when you bought. At the moment I suspect you don't have much legal protection, but the fact that no-one else can access the land probably gives you a good case if it comes to negotiating about the rent or purchase price.
If you want to sort it out, you should first ask your solicitor to explain exactly what sort of arrangement exists at present. He should be able to tell you what your rights are.