misslawbore
It's unlikely that ATOS will offer a home assessment unless your GP writes to them to explain why you cannot attend at their offices, so you should speak to them to see whether they will provide you with a letter.
Although the DWP can override ATOS to carry out a home assessment they will not do so unless you have first failed to attend, which will introduce a whole load of other problems to your claim, not least considerable delay.
One of the things you can do is to contact your MP and ask for there assistance.
Contacting your MP Gordon