Welcome to the club we’d all have preferred not to join. You’ll find plenty of information and support here. It’s a lot to take in, and I hope you have people who can support you as well as your husband.
My husband when diagnosed thought a lot of fuss was being made about nothing - it’s a common reaction. Unfortunately this disease does affect insight.
On the driving, you will need by law to notify DVLA of the diagnosis (and his insurers too) immediately. The insurers must be informed that he has been told not to drive pending the outcome of an assessment.
Once DVLA has been informed they will request and pay for the assessment - they will notify you of which centre they want your husband to go to. This can take a while - in our case, about five months. I don’t know which part of the country you are in, but there are centres dotted around. See
www.drivingmobility.org.uk/?gclid=EAIaIQobChMI0Kem5M_O_gIVQe7tCh16cAK1EAAYASAAEgK0IPD_BwE I believe a fee is payable if you approach a centre directly, but it will speed things up.
The assessment itself takes a couple of hours. We found the staff helpful and supportive, but also clear when their assessment results showed it was time for my husband to stop driving. The safety aspect was heavily emphasised, and helped my husband to come to terms with not driving any more. For each assessment I drove my husband to the centre and waited for him, which is advised because any advice to stop driving takes immediate effect.
A new diagnosis of Alzheimer’s doesn’t automatically result in not being able to drive. It is hugely helpful to have an independent opinion on the issue, and if he does ‘pass’ this assessment do accept any invitation for review. It lets you off the hook in a big way, and gives him someone else to blame if it doesn’t work out as he expects/wants.