Homeworking can be required as part of a job description for new starters, but if an existing office-based job is to be changed to homeworking, it should be a voluntary arrangement for both the worker and the employer.
The main terms of work are set out in the contract of employment entered into by an employer and an employee. One of those terms is work location. This can be changed only by mutual or collective agreement (though some employers may attempt to enforce changes by dismissing staff and then offering new terms). So you can't be forced to work from home, unless changes like this are provided for in your contract.
Some employment contracts include written terms known as ‘mobility clauses’, which allow the employer to make changes to your work location without your consent. Even if your contract contains this kind of term, your employer must still act reasonably, consult with you and set aside enough time before making any changes to enable workers to prepare, instead of forcing change on you. Otherwise, the employer is in danger of breaching the fundamental duty of mutual trust and confidence that is implied in every employment contract.
Sometimes employers take a strategic decision to let go of office space to cut costs, asking some employees to work from home instead. This is likely to create a redundancy situation, and those unable or unwilling to work from home should be offered a redundancy payment if they have enough service.
Forcing you to change your work location from office to home would be a fundamental change in one of your core contract terms. Check those terms carefully, including any mobility clause, and take legal advice before you decide what action to take.
Your employer must not discriminate when implementing changes to work location. They must also make reasonable adjustments for any disabled employees who are adversely affected by a plan to shift to homeworking.
As with most initiatives, homeworking is best introduced through mutual agreement. Someone forced to work from home is unlikely to be as motivated or productive as someone who does so willingly.