Charliecat,
This is what the link I posted says:-
Many people with severe mental illnesses drive safely. There are however, some mental illnesses for which extra precautions must be taken. People with personality disorders and alcoholism have the highest rates of motoring offences and are more likely to be involved in accidents. Therefore, to be safe on the road you must be aware of how your illness affects you and have the permission of the Drivers and Vehicle Licensing Agency (DVLA) to drive.
If you are diagnosed with a psychotic illness such as manic depression or schizophrenia and you intend to drive you must tell the DVLA. If you do not you will not be able to drive legally and your insurance will not be valid.
The DVLA will send you a medical questionnaire to fill in, as well as a form asking permission for them to contact your doctor or a specialist. You should always give permission, or you probably won't get a license. What the doctor or specialist says to the DVLA will affect that body's decision on whether you will be allowed to keep your license. You may even have to undergo a medical examination, which will be free, although you will have to pay any traveling expenses yourself. During this time you will normally be able to keep driving under section 88 Road Traffic Act 1998. However, if your doctor advises you to not drive and you choose to ignore this advice then it may affect your insurance cover.
The advice that the DVLA gives is different depending on whether you are having an acute episode or you have a controlled chronic condition.
acute episodes
The DVLA must be notified and you should stop driving until you hear the outcome of the medical enquiry. The license will usually be revoked until the person has been well and stable, compliant with medication and with insight into their condition for up to 12 months, depending on the severity and circumstances of the illness.
chronic mental illness
The DVLA must be notified but driving is usually allowed even in those who continue to have symptoms, and whose insight is limited. It is conditional upon compliance with medication and stable behaviour. Symptoms must not intrude or cause distraction while driving. If the DVLA does allow you to have a driving license, they may restrict it to a period of one, two or three years, after which you will have to go through the whole process again. In this way your illness can be kept under constant review.
incapacity
Incapacity refers to times when you are unable to make various decisions for yourself. In these circumstances medical professionals should inform the DVLA immediately and explain to you that they have a legal duty to inform the DVLA.
if you do not accept that you are unfit to drive
The doctor who has recommended that you do not drive should suggest that you seek a second opinion regarding fitness to drive. They should make the appropriate arrangements for this to happen. You will not be able to drive until you you have obtained a second opinion saying that you are fit to drive. If you do continue to drive when the doctor has said you are unfit to the doctor can inform your next of kin, and disclose medical information to the medical advisor at the DVLA.
changes in your illness
If your illness gets worse since your license was issued, or you develop a new medical condition, you must write to inform the DVLA of the nature of your condition.