If the police have been called to the properties in the past, it may be necessary to obtain a statement from the officers concerned. The police can be interviewed and called to give evidence in civil proceedings subject to paying the constabulary that employs them a fee to interview them, and then obtaining a witness summons to compel their attendance at the civil trial. If there is a dispute regarding a boundary, copies of your title deeds will be required. We may need sight of the solicitor's file that did the conveyancing originally. If you maintain that the neighbour's activities are making you ill, we made need a report from your doctor.
Litigation is costly.
It is worth checking your home contents insurance to see if you have any legal expenses insurance, which may cover the costs of the proceedings.