Coming from the United States, having been in the plumbing and heating industry for over 14 years and having just recently completing my ACS for domestic gas, I think that this whole premis of self certification is a joke. In under five months (and thousands of pounds) I, once I am Gas Safe registered, can do unsupervised work. For me this is a joke. There is no way you can learn how to be a good gas fitter in five months. I the US it was four years of supervised work before I could legally work on my own. Even after that, any job had to be inspected by city inspectors. Permits had to be applied for before the jobs started and the inspector could drop in any time. There were six inspectors for the City of Seattle. This ment that I had an inspector on site every two weeks. The quality of work I have seen here has been an eye-opener. 80% of the work I have seen would have been rejected by US inspectors and you have far more gas installations. Plumbing here is a different matter altogether. I'll bet that 90% of the plumbers here wouldn't know how to size a system based on fixture units or cross sectional area. The fact that you can go on a two week training course and call yourself a plumber is a joke.
I'm sure that after my rant I will be told to just go back to the US. I will be. There are so many other reasons for me wanting to go back to post on here.
Ferret is right. It shouldn't be called a registration scheme, it should be called a registration SCAM. That is exactly what it is. I have only been here a year and I know that.