I think the GP may be jumping the gun a bit here - as far as I understand it, they can't diagnose your husband.
From my experience with my dad, diagnosis is a long road. This may vary depending on where you live.
I would recommend you do ask to get him referred to the memory team if he is having problems with his memory.
Before this happens he'll have to be checked for anything else that could cause it - dad had to be on medication for low levels of iron for a certain amount of time before they would refer him as the GP said the memory team would not see him until it was certain his memory issues were not caused by another factor.
When he was referred, he was first seen by a nurse, then a psychiatrist. He was then diagnosed with dementia (unspecified, pending MRI), then had a MRI scan (fourth time lucky!).
After that the psychiatrist eventually read the scan, and dad was diagnosed with Alzheimer's, vascular and 'possible other' types - so, mixed dementia.
Dad has been unable to live independently for some time - he is completely disorganised and neglects any self care, although he is not yet incontinent - and has been in residential care for a year. We got the final diagnosis this month. He has also been prescribed some medication following this.
I didn't think he 'needed' a diagnosis 'per se' but as it turned out his lack of organisation has meant he left bills unpaid for months and we are still catching up with them. And he's been unexpectedly sued for non-payment. The diagnosis, will, I hope he useful for combating this. You don't know when something may happen and you may need to 'prove' he is ill. In my experience, people do not believe you without the official diagnosis.