Apologies for invading your forum, I'm not a teacher but asking on behalf of DH.
He is currently essentially an "unqualified" teacher. His background is as a professional musician (with a BA, then MMus) and he has gradually done more and more teaching and less playing. He's now pretty experienced in this role and is currently employed as a music specialist in a primary school.
He loves his job but the problem is he is already on the top of the TA/unqualified teacher payscale and without QTS he can never be paid more than this despite his postgraduate qualifications, many teaching courses/workshops attended and years of experience.
For him to go the PGCE route though would involve quitting the job he loves, and losing his income for a year, and then having to do at least one year of general primary teaching as an NQT before looking again for primary music jobs (which are not exactly common).