sorry, not sure if this is the correct place, but husband has to give employers an answer to this ASAP and I am hoping someone here has employment law experience and can help. Sorry its a bit long, and if it should be in another section I can hopefully get it moved, but I really need a quick answer as explained below.
Brief outline. DH has been signed off with work related stress since last May. Small company with 3 directors and lots of office politics, and (knowing he had a nervous breakdown 4 years ago) the company was on the verge of going under, and they were making it clear they wanted to force my husband who was/is the shop manager to leave. In the space of a month he was given 4 verbal warning for different things, all of them were untrue, but with no witnesses to prove otherwise very difficult to contest. Basically it was mind games. Our GP was very concerned and signed him off.
We have spent the last 10 months with him at home, very stressed, and almost agrophobic. It has not been a great time as you can imagine.
We saw a specialist solicitor last year who said he had a strong case for constructive dismissal, but at the time my husband didnt feel able to cope with a legal case and hoped that they would just make him redundant so he could get what he was entitled to after working there for 8 years.
He offered to take voluntary redundancy which they had offered verbally, but they refused to communicate with our solicitor (citing data protection act), and we didnt pursue that further at the time.
My husband went into his workplace two weeks ago to say he felt ready to return, but was told by one of the directors that they would need to have a meeting to discuss this, and he should get another sick note.
It has now come to a head as the GP feels the situation is not helping my husbands progress and sitting at home was now making him feel worse, and she signed him as fit to return.
He again went to his place of work, last week to inform them, and said he was fit to return today (Tuesday).
He received a letter last week saying he had to attend a meeting with the directors and company solicitor yesterday. He went, and was in there for ten minutes. They told him they wanted to make him an offer of compensation to pay him off to leave.
Now for starters, I believe that as he is now fit for work , from today he should be back on full pay, and this is what is classed as "garden leave" as he was willing to return, and they told him not to.
They rang just now and offered him £2500.
He is on a salary of £28500, has been there for 8 years, and gets 28 days holiday a year. He had only taken 2 days holiday last year (Jan - Dec holiday rota) before he went sick, and I know he continues to accrue holiday pay while sick, as well as not losing previous years holiday if he is off sick.
We are sure he is entitled to more than £2500 and they want a call back this afternoon. 
He is now almost back at square one with his stress and sitting here shaking, so I would really really appreciate anyone who can give me a rough idea of what the minimum is he should be given.