We cheated! We were part of the Church which was already registered with the Charity Commission, so most things were covered by our own Constitution. But I do fully agree that it is essential to have a formal set-up even if you are a very small group. Sometimes one can “piggy-back”, like us, with a ‘parent group’, but whatever happens, one must do things ‘properly’. I know, from talks with Funders that keeping of proper annual accounts are essential, for example.
I think that owning or building property could be a nightmare. Apart from formal advice, I’d ask any local groups who have done this for their experience. Smaller things tend to be Scout Huts (for example) but they would have a National group for advice, so possibilities might be those concerned with building a village hall, for example.
We did a huge amount of building & renovating (best part of a million over 10 – 12 years) and you have to be absolutely sure of finances and also that the project is overseen properly. My last item was replacing od 2 toilets which took 3 times longer than the time quoted, so there are masses of snags!