The 300 route is not necessarily all doom and gloom, AH Helicopters operate at least 1 from Dunkeswell. Bournemouth Helicopters also had one last time I spoke to them. Helicentre Liverpool have one.
Cabair Helicopters bought two brand new 300s earlier this year, and operate them from Blackbushe and (either rochester or Elstree, cant remember).
I think they were considering more dependant upon how those two worked out.
I don't the Cabair ones will be working as hard perhaps as the OAT or BHHs ones did initially as they obviously have some students mid R22 course and they'll probably want to finish on that type (my assumption).
However if you look at the number of R22s in schools compared to everything else the conclusion does seem to be that if you need to instruct you'll probably want an R22 Type Rating as well and FI rating.
As helimutt says there are people out there who fly overweight, but its not their licences that'll be up for review, if and when you get caught doing it (I know you didn't suggest you would, I am just making a point albeit badly), chances are no one will even look until an incident occurs.
GS