Generally speaking, yes. However, there are exceptions.
As you are still employed, the default position is that you must work when your employer asks you to and/or when you are contracted to. If you are shielding in line with public health guidance (and received the letter from your GP or NHS), off sick or self-isolating, you would not have to return to work of course.
If you are concerned that it is not safe to return, you should speak to your employer in the first instance to voice your concerns. If they have put in place everything they can to ensure social distancing and hygiene measures are in place, there should be no reason for you not to return.
However, if the employer has not put the appropriate measures in place to ensure the safety of its staff and you refuse to return to work; if you are dismissed because of this, it could potentially be automatic unfair dismissal. However, you must believe that there is imminent and serious danger. If the employer has put in place appropriate measures in line with government advice, it would be very unlikely that an employee could argue imminent and serious danger. It will depend on the circumstances of the measures in place, the employee’s own health concerns, and the wider risk of people contracting COVID-19. As the number of cases reduce and we move through the phases of easing out of lockdown, the threat level reduces for employees contracting COVID-19 at work.
If you refuse to attend work without a valid reason, it may be treated as an unauthorised absence and the employer could take disciplinary action. However, disciplinary action could be ‘detrimental’ treatment, which may give rise to a detriment claim for the employee. This is a complicated area of law so I would always advise taking legal advice.
Given the potential risk, employers should carefully consider an employee’s justification for refusing to return to work before taking any action. Again, taking legal advice would be recommended.