Re: http://www.techniquetraining.co.uk/courses/aircon/tacr10.html
You will need your F gas as a minimum.
A two week course isn't going to turn you into an engineer, if its a good course what it will do is give you a foundation on which to build.
I don't know what employers in general look for in a new employee, personally i'd want to spend a day or two on various sites to see if i thought they had potential and to see what they are like as a person.
I've 'trained' two appretices, one came out of the army, did a months course and joined our old company, he's now a senior engineer with another company. The other apprentice did a short course with pendle, having come from the building trade, he is now my business partner.
As an example i think it wasn't until their second year that i allowed them to do flares let alone any brazing :D
Good luck!
Jon :)