My mental health has been taking a big hit

So I (16M) have been struggling with my mental health for about a year or so, and I am trying to reach out for support however I cannot travel to my nearest walk in centre due to my sister being in school and the limited hours in which it is open, and recently my mum has had 2 major mental health crisis episodes where she has had to go to hospital (The suspected causes being Bipolar), and seeing her having these issues has really screwed up my own mental health, and I'm not sure what to do. (For anyone who may recommend companies or organisations/charities I am a UK resident and cannot travel far from where I live in Norfolk)