MFWF
'as long as it is retainer not OTE'
Sorry to disappoint you again but I'm afraid most schools pay by the hour flown. Some will offer salaries or £500 per month plus flying pay but they tend to go to the more experienced instructors (derestricted with No Instrument restiction ). It will take you about a year to reach this level of experience at a reasonable school.
At the last school I taught at there were no intrument instuctors becuase it cost £1000 to get the restriction removed and the school only paid £5 per hour more for the lessons. On basic economics the hour builders figured they would never get it back.
Go and talk to some cfis and find out what they say.
There have been threads on flying pay on PPRUNE.
If you want real money do your FI at DEFTS and try to get a job there after. I believe they pay reasonably well (22K+).
Good luck.