Health and safety law applies wherever you are, the only criterion is that you are at work.....so that includes home, if you're working at home. Employers are responsible for ensuring that the work being done at home is safe, just the same as at the office. Of particular importance are electrical safety, slips/trips/general housekeeping, and display screens. On the latter subject, an interesting and timely article appeared on the BBC today on this very subject, it saves me repeating it! One thing to add; even though an employee is working at home, it's imperative for the employer to have a relevant (if brief) policy, and a means of assessing and monitoring this.
As always, if you need any help with this, you know where we are.