At the very least you should talk about it with your friends and report his behaviour to your uni if he's a student there. Tried to put information relevant to your post in bold but it's probably useful to read it all.
The Equality Act 2010 says someone sexually harasses another person if they:
Engage in unwanted conduct of a sexual nature and
The conduct has the purpose or effect of either violating the other person’s dignity or creating an intimidating, hostile, degrading, humiliating or offensive environment for them.
This unwanted sexual conduct can happen in person, on the phone, by text or email, or online. Both the harasser and the victim or survivor can be of any gender.
Sexual harassment includes a really wide range of behaviours, such as:
Sexual comments or noises – for example, catcalling or wolf-whistling.
Leering, staring or suggestive looks. This can include looking someone up and down.
Sexual innuendos or suggestive comments.
Unwanted sexual advances or flirting.
Sexual requests or asking for sexual favours.
Sending emails or texts with sexual content – for example, unwanted ‘sexts’ or ‘dick pics’.
Sexual posts or contact on social media.
Intrusive questions about a person’s private or sex life.
Someone discussing their own sex life.
Commenting on someone's body, appearance or what they’re wearing.
Spreading sexual rumours.
Standing close to someone.
Displaying images of a sexual nature.
Unwanted physical contact of a sexual nature – for example, brushing up against someone or hugging, kissing or massaging them.
Taking a photo or video under another person's clothing – what is known as 'upskirting'.
Sexual harassment is a form of unlawful discrimination under the Equality Act 2010.
This means that people are legally protected from sexual harassment in certain places – for example, at work, on transport and at schools, colleges and universities.
Some important things to know about sexual harassment and the law:
It is the person receiving the sexual behaviour who decides if it’s unwanted – NOT the person doing the behaviour.
It doesn’t matter if other people think the unwanted sexual behaviour is okay. Or if it’s common in the place it’s happened in.
It can be a one-off incident or repeated.
Just because certain sexual behaviour was welcomed or not objected to in the past doesn’t mean that it can’t become unwanted. Or that other sexual behaviour is wanted.
When sexual harassment is a crime Some forms of sexual harassment automatically break criminal law in England and Wales, and are therefore crimes. These include:
any sexual harassment involving physical contact (this amounts to sexual assault in English and Welsh law)