Gloucester, Cheltenham and Worcester all run along the M5 so I guess that's why they're connected together that way. And I think a few people from Worcester joined Gloucestershire group so they spread up that way. (Is that correct Andy?)
Herefordshire joins onto Wales so there's some overlap between those two groups - mainly me!
The meetings for the two groups are probably a similar distance from you so I think you should go to both, then you could set up a West Midlands group, fill in the gaps and join us all together!
At the moment Herefordshire are planning on having members meetings quarterly with training and events in between so not due for another one for a little while but will keep you informed.
I'll do my best to get over there to the meetingnext week as I've been meaning to for ages.