Carby, you do talk some rubbish! If that is your attitude to employees, I am amazed that they are stupid enough to stay working for you!
Amandabethy, check out www.acas.co.uk and even call them for guidance about your employment rights. Their advise is free and you will be well guided by them.
In principle, your employer sounds like he is being unrealistic and I would suggest that, initially, you have a chat with the boss first and politely / calmly explain the realities of what is being proposed. They may turn out to be more reasonable than you think (hopefully).
Come what may, you cannot be expected to cram 5 days work into three. If you did that and it made your job miserable, it could possibly be interpreted as 'constructive dismissal' in a tribunal.
Good luck