Recently diagnosed with ms

Hi I have just been diagnosed last week and informed my boss of what is happening I want to return to work but boss is asking for a letter from my gp stating that I am fit for work I be been told by gp reception that I can’t get a fit for work letter and to fill in a self assessment sick note that is all I can do . I’m confused as I want to return to work I feel fine at the moment but can’t return until I get a letter that I’ve been told I can’t get . Any help or advice would be massively appreciated thanks for reading

have you told your employer that you are unable to get a fit for work letter because the surgery is unable to write one?

sound like they (the doctor’s surgery) are nit picking to me.

maybe if you self certified sick, then perhaps they would agree to write you a fit for work letter on your return?

Does your workplace have an Occupational Health service to refer you to?