Hi Abi
You have plenty of people here who can help you. You should try not to miss any school. I had P all through primary and secondary schools. I was slightly luckier than you cause there were 3 of us with pretty rotten P. The school uniform can be adapted for covering up P. You just have to think how to get around it, unless your school makes you wear socks and a skirt personally I would be wearing trousers or black tights and even tracksuit bottoms for PE. All schools should have a policy for people with P or E. I know that in Fife all pupils can get access to a medical room to apply creams or moisturise in privacy during the day and are automatically allowed to cover up for PE or be excused if the skin is raw and sore, It is also important for the school to be able to organise your exams. Did you know that if your skin is bad you are allowed some extra time if you need to get up and stretch having daily treatment at hospital is a medical treatment and can be used for appeals! my friends daughter has has bad E and sometimes can't hold a pencil she was given a scribe and extra time to allow for someone writting down her answers. Please don't despair.
I know exactly how sh~~ty you feel when you have P and can't get the same clothes as your friends and yuou feel; that everyone is saying look at her whats that. I still have a phobia about changing rooms in shops, I never try on clothes unless someone is with me and I'm 47.
Its hard being 17 and having P but there are ways of covering it up you'll have all the help you want here.