Well Cesspit I think that 10 to 16 quid per hour is about the going rate for PPL instructors. I get £12/hour tacho time (nothing for groundschool) and no retainer as a part time FI.
I had toyed with the idea of giving up my very well paid day job to try and get a full time FI job, but have decided against it as the pay and conditions are totally crap. I'm not sure if I'll even continue with the part time instruction, but I'll definitely be going and paying to do some quality hour building.
The way I see it there are plenty of instructors out there with the magic 1000 hours and no proper job.
At the end of the day it depends upon how much money you earn in the week, and whether or not you can afford to pay for flying to keep everything current.
Good Luck
aerotowman.