If theyve been in talks for 3 months Dot then theyve very probably been doing it correctly as this would be the consultation period. He could ask what the selection criteria were (e.g. a points score system, last in first out etc) but as theyve been doing this for 3 months I imagine they have got the procedure right as they havent just jumped straight in with redundancies.
His contract will tell him what the sick pay arrangements are.
It may also say in his contract that any annual leave is taken during the notice period - but it would actually need to be stated in this contract for them to do this, so again check the contract. It complicates it somewhat if he's sick and his contract says he must take his holiday during the notice period. Personally, if I were his boss I'd play safe and pay the holidays as extra.