Hi. I'm chair of FOG in South Wales. Perhaps I can help?
Legal requirements. As a minimum you need landowners permission for the range, including any downrange areas where rockets may drift. Its a good idea to inform your local police station so that they know what's going on.
Airspace is a big issue in the southern UK. You cannot locate the club within 5 miles of an airfield or launch into controlled airspace. You can launch into uncontrolled airspace and it is prudent to issue a NOTAM (instructions are on the UKRA website).
Its sensible, but not a legal requirement, to locate your club somewhere that is inaccessible to the public such as a private farm. It can be very inconvenient if you're always having to stop for people walking through the range. It can be dangerous to them if you can't see them coming.
Insurance. BMFA insure individuals. At FOG we insist that everyone if a BMFA member. As the organiser of the launch you are liable for whatever happens that falls outside the scope of individual insurance. As an example, of someone is injured at your launch you could be held liable. BMFA will insure a club if it is affiliated to the BMFA. To do this it must have a committee, officers, constitrution and at least 5 members who join BMFA through the club. This can be hard for a new club but it saves your persoanl liability.
Certification. If you want to do certification then you need UKRA qualified RSO. FOG doesn't do UKRA certification or follow their safety code. We found it impractical to get sufficient RSO qualified so we fly according to the BMFA code and have a local RSO scheme.
Special Requirements. Stuff that we've found useful are a website, FaceBook page, access to good met forecasts so you can decide whether to cancel events if the weather is poor. A good email list is useful for announcing news and changes of plan. If you want to talk further then PM me.
Phil