stocker,
If you do your flying in Scotland I am amazed that you "hadn`t thought about it before and just assumed that as long as I stayed below cloud base I`d be ok.".
Personally, unless I'm just doing circuits, I have a 1500' absolute limit, (or 1000' above the highest ground anywhere near my flightpath). Anything less and you stand a good chance of flying too low over a built up area or within 500' of property, people etc.