You are protected from sexual harassment in the workplace by the Equality Act 2010 under the section of prohibited conduct.
The Equality Act defines Sexual Harassment as: Unwanted conduct of a sexual nature which has the purpose or effect of violating someone’s dignity, or creating an intimidating, hostile, degrading, humiliating or offensive environment for them. Something can still be considered sexual harassment, even if the alleged harasser didn’t mean for it to be. It also doesn’t have to be intentionally directed at a specific person.
It does not matter how long you have worked for your employer, or whether you are a permanent employee, an apprentice or trainee, on a fixed-term contract or supplied by an agency, you are still protected by this legislation.
This TUC booklet here describes the offence, its impact and the rights you have to fight back if it happens.