I'm very sorry to hear about your predicament. Although it is possible that an ophthalmologist could have made an error during the treatment, it is more likely that you are having an unfortunate reaction to the treatment itself.
Did the ophthalmologist mention macula oedema? Some people develop this following laser surgery for new vessels. It can cause blurred central vision which often recovers by 3 months following surgery. If it hasn't recovered after 3 months, further treated may be needed - did the ophthalmologist mention this?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3526904/
Presumably, the advice about being below legal driving requirements is based on your central vision (as you haven't mentioned taking a field test). If so, and if the central vision improved (either following treatment or spontaneously), the driving restriction might only be temporary.
I understand that you feel very angry about your situation and certainly, if there had been any errors made by the ophthalmologist applying the treatment, you should be due some compensation. However, do bear in mind that there are inherent risks with any treatment and these have to be balanced against the risks of not having treatment. In general the risk of sight-loss due to treatment is much lower than the risk of sight-loss from not having treatment but there are no guarantees, unfortunately. Although your eyesight seemed fine before you had the laser, the fact is that those new vessels could have bled at any time and made your vision much worse than it currently is.
I suggest you go and see your GP and talk it over with them - they should have had a detailed feedback letter from the hospital eye service which may make things clearer.
Out of interest, were you already under the care of the ophthalmology department when you had to go to A + E? If not, there may need to be an investigation as to whether the new vessels were missed at your last eye screening.