please help☹

I am 13, nearly 14 and I really need some help🤔 My Nan died in July and My grandad is absolutely heartbroken and I hate it.  I live in a bad area on a council estate with my mum, stepdad and baby sisters. I love them all dearly and I think they feel the same. I get on well with my stepdad. The thing I hate about my home life is that my parents get drunk regularly and it's horrible. I have always stayed at my grandparents house on the weekends and I still continue too. I would happily leave my school and start a new school. I would be much happier here but I don't know how to tell my mum because she would be heartbroken and feel it's her fault. The main reason for moving would be I hate my school, I hate the area I live in, I hate the fact that my grandad is always alone and I love where he lives and it would be a much better life for me.. what do I do?