There are many Roman sites in Great Britain that are open to the public.
There are also many sites that do not require special access, including Roman roads, and sites that have not been uncovered.
See East Sussex, West Sussex Inveresk Mithreum, by Musselburgh, near Edinburgh, link: https://www.cambridge.org/core/journals/britannia/article/mithras-in-scotland-a-mithraeum-at-inveresk-east-lothian/544B6233F7F06415EE049C60A827C3C0