Universal Credit- getting a sick note

As my local council no longer deal with housing benefit, I applied for universal credit (which encompasses housing benefit and income support). The problem is that as part of the claim for universal credit, the DWP want to see a sick note.

a) Unfortunately I haven’t been able to work for 3 years so although I can understand the reason behind it I do find it slightly offensive that I have to chase up my doctor for a sick note.

b) My neurologist’s secretary advised me that I need to contact my gp for a sick note. This is rather pointless seeing as though I haven’t met my gp for a few years. I see my neurologist every 3 months as part of my lemtrada treatment so surely my neuro is best equipped to provide a sick note.

c) what length of time does the sick note need to cover?

D) I am scared of DWP regularly making life difficult for me & asking for a new sick note continuously. I’ve read testimony from claimants who have only been provided a few days in which to get a sick note. This is compounded by the fact that it takes several weeks in order to get an appointment with my gp. So I envisage a situation where my benefit is potentially cut/delayed.

please advise guys. Just the thought of the possibilities is frightening me.