COTAG had a few members where I used to work (RAF Kinloss)
As far as I can see (other people said exactly the same thing last year!) If the weather gets too bad for the emergency services to cope, then the government will request MACP (Military Assistance to the Civil Powers) or MACA ( Same thing, but Civil Authorities)
This means that properly trained people, with properly equipped vehicles will go and do this sort of thing. it is government funded and uses military vehicles and personnel.
As far as I can see, if you go out as part of a response group, you are undoubtedly helping out the local community, but the government is happy to let you pay your money on fuel / kit / additional Business insurance etc.
Not my cup of tea, but i'd always stop and help pull someone out if they were stuck, just as Id always stop and help if I approached an accident.