Some facts:
The market is over-supplied with newly-qualified FIs for JAA PPL training (read the FI forum).
There is not a large market for full time FI(M) - most are part-time, and the ones that are full-time are probably making £25,000 tops, I think you'll find. A small number may do better than that, but given UK winter daylight, weather and customers you can't bank on it.