Although there is no automatic right to go onto your neighbours land to carry out repairs, if you ask for access, and you are refused then you can apply to the court for an order under the Access to Neighbouring Land Act. The court may make an access order if you need to carry out reasonably neccessary repairs that cannot be carried out, or would be substantially more difficult to carry out from your own land. The court will add all sorts of conditions to the order for the protection of your neighbours interests.