Avtech 2000 do the City & Guilds course
http://avtech2000.co.uk/index.html
I would say that for starting out it isn't worth it at the moment as think it is upwards of £700 for a qualification and to be honest it probably isn't worth it for an Ops Assistant job. But it could be something you could take in conjunction with on the job training whilst in a job. Wouldn't do it before you even have a job. Others may disagree!