Defining the regions was a lot trickier than I thought it would be. I looked at the way regions were split by the BBC, the Office for National Statistics, The National Trust and various other organisations. In the end The Boundary Committee for England, which is part of the Electoral Commission, seems to have the best way of dividing up England. More importantly it's easier to 'drill down' into their system online to be exact if necessary.
England Region Map

In reality I don't believe there'll be much ambiguity but I'd prefer to head off any problems with regions at the start. This map will give you a visual guide and further details can be found at The Boundary Committee for England. *will open a new window

Scotland, Wales, Northern Ireland and the Republic of Ireland I'm sorry but if there is more demand from your respective areas then I will look at dividing you up further then.