Pin Head,
The service isn't interested in people just building hours, they are looking for folks who are devoted to instruction, putting your student first. You don't just go and fly to put hours in your logbook, you go and fly to get the lesson across to your student!
So if you want to hours build go para dropping or tugging (I know Booker are looking for people).
If you want to instruct, put your logbook away and call up some of the FS schools such as Bodmin.
I do hope that you haven't spent your 700 hours instructing just getting Bloggs to fly the aircraft S+L on long cross countries.
Good luck in getting what you want,
Vigi.