I don't know your area but some things are nationwide.
When it comes to paying for care, a financial assessment will be made of Mum's finances only. Any joint account will be considered as 50% hers regardless of who puts what in. The house will be disregarded as long as they both live in it, so even if she had to go into care, it will be prevented from counting as it's still your Dad's main home.
If your Mum has more than £23,250 in savings, she will be classed as self-funding. Between £14,250 and £23,250 Social Services will contribute. Under £14,250 care should be free, though state pensions and half of private pensions would be used towards the funding.