Tony M,
The most obvious place to look is on Aviationjobsearch.com under Operations and Airline/Office Jobs.
If you have not already used this website, you can't really go wrong as most major compaines advertise through them.
If you are in the LHR area, then also try and get a copy of the LHR Skyport Newspaper which comes out every Friday and will be available in cornershops, petrol stations and all sorts of places around LHR.
Good luck,
Punch
