Under the Act, an Adjoining Owner(s) and/or occupier(s) must, WHEN NECESSARY, let in your workmen and your own surveyor, to carry out works in pursuance of the Act (but only for those works), and allow access to any surveyor appointed as part of the dispute resolution procedure.
You must give the Adjoining Owner and occupier notice of your intention to exercise these rights of entry. The Act says that 14 days' notice must be given, except in case of emergency. If access is necessary to carry out the notified works you may wish to include this requirement in the notice that you serve when seeking consent to carry out the works, so as to avoid any dispute in this respect at a later stage when work is underway.
It is an offence, which can be prosecuted in the magistrates' court, for the occupier or other person to refuse entry to or obstruct someone who is entitled to enter premises under the Act, if the first-mentioned person knows or has reasonable cause to believe that the latter person is entitled to be there.
If the adjoining property is closed (for example an unoccupied property) your workmen and your own surveyor or designer etc. may enter the premises by breaking open a fence or door, if they are accompanied by a police officer after following the Act’s procedures.
You should discuss access for works with your neighbour. It is often in the best interests of the Adjoining Owner to allow access voluntarily to build a wall or to carry out works for which there is no statutory right of access, as this will allow a better finish to the side of the wall that they will see.