Unless there is an express term in the contract of employment permitting the employer to make you work from home the employer needs your agreement. Failing this, the change would be a unilateral variation of contract, which you would be entitled to reject - although doing so could in time lead to your employment being terminated.
If you accepted such a variation and, on the assumption that you would still be an employee, you would be entitled to the same contractual and statutory employment rights as you would if you were working at the employer's premises. So you and the employer would be subject to duties and obligations arising from express and implied terms.
If you want to agree to the employer’s proposal, you should negotiate an appropriate incentive. Given that the employer will be saving costs by not maintaining a space for you at work (essentially at your expense) you should be in line for a substantial payout.
You would be entitled to reimbursement of expenses necessarily incurred during the course of your employment. Examples of these might include:
Before agreeing to work from home, you need to think about all the implications of the changes and discuss the issues with someone experienced in the associated pressures, such as isolation and productivity. Seek advice or information from a union rep if you have one.
There might be capital gains taxation implications if part of the house was converted for occupational use. The Regulations are complex and further advice can be sought from your local tax office.
