At the start of your degree, you are assigned a tutor, a member of staff who is there for pastoral care and to give you a friendly link to the faculty staff. They have a responsibility to give you advice and direction, and they all love physics, so don't shy away from contacting them or just dropping in for a chat. Even if they can't directly help you, they will be familiar with the lines of support offered by the university. If you have a problem and you're not sure where to go, your tutor is always a good place to start.
There also exist senior tutors, who don't have specific tutees but are there to advise the tutors. If you don't feel comfortable going to your tutor about something, you can always go and see one of the senior tutors for help. It is also possible to be assigned to a different tutor if you really have a problem with your current one.
The university has a dedicated service to support students with disabilities, mental health problems, and specific learning disabilities. Their expert team can provide advice and support through face-to-face meetings, over the phone, and Skype (with the exception of counselling appointments). They also work closely with local services, so if you're having trouble but aren't sure where to go, Enabling Services is a the place to start.
The advice centre offers advice on all of those things you feel you ought to know by now but all of a sudden you're an adult and nobody told you and you've got to deal with adult things by yourself even though you're basically a baby but with bills and responsibilities. They offer guidance on topics such as finances, housing, emergencies, acadaemia, and all sorts.
The WPN is a group within physics which aims to promote the career development of women in physics and to champion gender equality and diversity within the department. An important part of this is supporting and encouraging undergrads by organising events focused on wellbeing and networking (which is a fancy word for chatting over coffee and board games) as well as putting on talks by prominent scientists and generally being exceptionally friendly to everyone. Do note that their events are not exclusively for women!
They have a webpage and a presence on social media.