Hi Peter
You might want to speak to a specialist welfare advisor - to see what benefits your brother and sister-in-law are entitled to. You can try and see if there is a service available in your area.
advicelocal.uk/ One benefit your brother could apply for is PIP - which is a non-means-tested benefit. I am assuming that as his cancer is currently at stage 2 he has not been given a terminal diagnosis at this stage and therefore his application will have to go through the normal process, and it won't get fast-tracked.
In applying for PIP they are not interested in the condition/s per se - they will be interested in what impact his cancer has on his daily living/and or his mobility.
If you have a look at the Guide to PIP Claims and Reviews, it will walk you through the whole process of how to apply. This can be done online or by a form sent by post. It's impossible to tell you how long the process will take, though they are trying to prioritise new claimants.
benefitsandwork.co.uk/guides-for-claimants/pip BIS
