I'v no real experience, but certainly finding a venue is probably the hardest part and overcoming the suspicions and misconceptions of the public and/or local council/police).
I think it's a toss up between keeping it very small and informal (assuming permission from the land owner) or, if possible cultivating contacts with the locals/council, maybe with a have a go or a demo, (pizza and beer may be needed). I'd strongly suggest keeping it to wooden bow only to minimise overshoot as compounds etc (spits on floor) can easily shoot 1/4 mile.
Start small and low key if possible.
Our "club" is just a few fields where we rove with permission of the farmer for a fee... we are not allied to any official organisation, I don't think there is any specific insurance and numbers are normally between 8-15.
It also depends on what sort of archery... target, field or roving.
If it's for roving and longbows only, it may be worth looking at/contacting the ILAA.
Dunno if any of that is helpful.
Del
PS. Membership of any archery organisation (even if it doesn't cover what you are doing) may be helpful.
E.G. I'm NFAS and ILAA. So if I get stopped by the police, whilst driving carrying bows ,or maybe testing a flight bow on the M11
I can at least use the membership as some sort of proof of competence. (Being bald and nearing 70 also helps rather than being a leary 18 yr old
)