This guide goes through the main things to be aware of if you are planning a protest on private property.
The police have the power to arrest people for criminal offences. Remember though that, even if convicted, first time offenders would be very unlikely to receive the maximum penalties.
If you are planning a long-term occupation then it’s good to be prepared for being faced with a Possession Order and an Injunction.
For a more detailed guide, see Netpol’s Guides on Policing and the Law for Campaigners Against Fracking