Mike is correct in stating that RAF entance requirements are rather rigid; however, ex-RAF QFIs have not been used exlusively for contract civilian training. Agreed most of those employed on the Hunting contract for JEFTS were ex-mil but some were also civilian FIs including a former civilian FI of mine. I doubt you would have any chance whatsoever of getting back in to mil flying but stranger things have happened. A 38 year navigator friend was recently awarded his wings and the RAF has recruited aggressively from the RNZAF. There's never any harm in trying although Careers Information Offices are unlikely to have anyone which sufficient knowledge; you would need to know someone on the "inside."