nalit . calm down, you have got yourself into enough trouble already!
alyo You will get a criminal record if this goes to court , you will have to pay for the damage and pay compensation as well. In addition you will get a fine or community service.
Trespass is a civil offence not a criminal offence ( like criminal damage) you can only sue for damage caused by the trespass not for the act itself , you can do nothing about that apart from asking him to leave.
Your 'no parking' sign is worthless it has no meaning in law, only a local council can designate a no parking area.
The only legal way you can stop people parking on your drive is to buy parking posts / bollards and use them to block access. Get the type that are concreted into the ground and have a hinge and lock so you can lower them when you need to use the drive.
You are going to have to apologise and offer to pay for the damage and hope the guy will drop the charge otherwise you WILL get a criminal record!