Ian - it's legal advice you need first here as to whether you have acquired a legal easement over time. If you have satisfied the legal requirements then our PG 52 explains how to then apply to register the claim -
Easements claimed by prescription (PG52) - GOV.UK
Land registration is complex, designed to protect legal and financial interests in property. There can be significant consequences for any error. Please consider seeking legal representation. Before making an application without legal representation, it is important to consider the benefits of using a conveyancer.