No mate, I always ask when joining if they mind me popping an ad in every week. Never had a refusal. Just good manners I suppose, and it must make a good impression as others just spam, and as an admin, that must be annoying.
Over here, it's easy because the Brit market is compact and has many pages and groups. Not sure about areas in the UK mate. Perhaps local hobby groups, riding school groups. Local rugby team groups and other sports. etc etc
One I post on is a police page.