JimBall is correct.
In England & Wales, a mere trespass is not a criminal offence.
The "Trespassers will be prosecuted" signs with which anyone who lives or has lived in the countryside will be familiar are meaningless - but probably effective because most people don't know they are meaningless.
Some here may be old enough to remember the 1982 incident when an intruder got into Buckingham Palace during the night and sat on the Queen's bed chatting to her. He wasn't prosecuted - he hadn't committed any offence.
The law started changing in 1994 to deal with certain specific problems but, even it's current form, simply going onto someone else's property is not a criminal offence.
Trespass is a tort, and the victim of a trespass is entitled to sue for damages to compensate him for any loss/damage he has suffered and, where appropriate, an injunction will be granted to prevent trespass continuing.
FL