Yes. A nationwide process server works through a managed network of vetted local agents, so a single instruction covers any address in England, Wales, Scotland or Northern Ireland without the instructing firm having to appoint separate suppliers county by county. One case manager holds the file, and every attendance is evidenced to the same standard.
For civil proceedings in England and Wales, service and proof of service follow Part 6 of the Civil Procedure Rules regardless of where in the country the attendance takes place.