Unfortunately, in the UK, bullying isn’t a legal term. As awful as it is, the basic act of bullying isn’t illegal. Except, in a few cases.
When it involves a protected characteristic like age, race, religion, etc. As bullying can be intimidating or offensive, under the Equality Act 2010, bullying based on a protected characteristic falls under harassment. That makes it illegal.
Under the Equality Act 2010, you don’t have to be the person getting harassed to have a legal right to complain or even take it to Tribunal. Because this type of behaviour can create an intimidating, hostile or offensive environment for you, you have the right to complain about it.
So while bullying is technically not illegal, there are ways you can fight back against bullies in the workplace.