Advice needed: worker's rights

I have been absent from the forum for a while as a wobbly week turned into a series of wobbly weeks. It has ultimately led to my dh being hospitalised. At a minimum it will be a week or two, but it is more likely that he will undergo ECT over a six week period before being transferred to a specialist PTSD program that will be for about three months as a resident. Up until our tr to the ED on Sunday night, he was in full time employment. What rights does he have in regards to his salary during this time? Obviously, his available sick leave will cover some time, and he does have some annual leave available. Can his employer terminate his employment? What would happen if he ran out of leave? Would he be able to get any salary or would we have to look at going on benefits? This is all new to me, and I don't know where to start.