I'm not a Nelly No-mates in my personal life, but I find my colleagues cliquey. What can I do?
Have you discussed this with your tutor? He or she should have the experience and knowledge of your school to help you take an objective look.
It's important for you to bring this into the open, because if you don't have a good working relationship with your department you are not going to make progress as a teacher. Everyone in this scenario has something to learn about professionalism and communication. If you're "never informed of anything", there's an organisational problem for your head of department to address.
Have you done something irritating? Are you super-efficient and make sure that everyone knows it, or so inefficient that colleagues have to carry you? Do you ask for help? Work colleagues like nothing better than being cast as experts - or are you presenting yourself as self-reliant and impervious to the practices that work for others? Again, seek an objective view.
A school is primarily a workplace. It could become the centre of your social life, but that would be a bonus. Friendship and professionalism can grow together, but it's possible to work well with people you never see outside school, as long as you're communicating.