In the UK you have to notify the government department responsible for issuing licences if your injury will affect your licence. However, much like in Canada once you loose it getting it back is more difficult and when you do - car insurance goes through the roof.

Have you thought about getting an independant assessment of your driving ?
Over here there is a scheme where drivers can be assessed independently before deciding to notify the government. It may be useful to have in your pocket when you go to the clinic.