Assuming that he is found liable for everything then his insurance will have to pay for everything - your car, the other guy's gate, the other car, everything. You may have to initially pay an excess, but this will be reimbursed.
Asuming his case goes to court, you would likely only be called to give evidence if he tries to worm out of it. Chances are he will please guilty ('no contest' would be the US equivalent I guess) therefore no formal hearing, and no need for you to be there.
Vicky