You could always call yourself Biomedical Engineer/ Technician, Electro-Medical E/T, Broken-Heart (machine)repair man. In fact you can call yourself anything you want as long as it's not a "Protected" title. If your management are happy that you are competent to do your job then carry-on mending!
This is precisely what you
won't be able to do, in the same way you can't call yourself an x-ray photographer and take medical x-rays, unless you're registered as a radiographer (or supervised by one). Staff whose work is supervised are unlikely to make any more than band 3.
Personally I don't think registration is an all good or all bad thing as it is supposed to ensure everyone working in the field is competent to do so (good thing) but is an unwieldy and expensive way of doing so, and probably won't achieve the goal. However it is coming (eventually), and sticking your head in the sand is the best way to get your bottom kicked.
