Hello wibblum and congratulations on your successful MR.
Even more good news is that SDP is not subject to any assessment, merely a check that you eligible for it.
If you have a look on this link and scoll down a little bit it will give you information you need.
www.gov.uk/disability-premiums/eligibility.
Most of it is very straight forward, unless you have someone claiming either carers allowance for looking after you or they get the carers element of UC for caring for you, in which case you are no longer eligible.
If you are eligible SDP is a supplement to your ESA payment. And just to be clear - there is no medical or medical questions!
I hope that helps
Catherine
