Fund raising advice

GlasweJen

For the fundraising I think you will need to set up a charity and deal with all the admin that goes with that, that will help in some ways as employers may match funds raised for registered charities.

Detroit

Generally, it is not advisable to resign from your job due to health reasons. It's usually in your best interests to remain employed, providing sick notes if unfit for work and receiving any contractual and statutory sick pay you're entitled to.
Eventually your employer will dismiss you as you cannot do your job due to your health, but this can take a while, and meanwhile you retain a level of income.
I believe that any money you make from fundraising would be likely to be treated as income or gifts, but either way unlikely to be ignored for means tested benefits purposes. However, if your partner has income, you probably wouldn't qualify anyway, unless you can get CBESA.