If you have notified the DVLA of your medical condition and they have written to you to say that it does not affect your driving, then you are legal to drive.

However, if you have not yet received a response, the DVLA has specific guidance on driving while waiting for a medical decision, which you can read here: assets.publishing.service.gov.uk/government/upload...f

In short the guidance says that you must meet all the following criteria: a doctor or healthcare professional must not have told you you are unfit to drive, you have held a valid driving licence and must only drive vehicles in categories you were previously entitled to drive, you meet any conditions specified on your previous licence, you are not currently disqualified and you were not disqualified as a high risk offender after June 1st 2013.