This might be the biggest change of your life, coming to University!
You need to start preparing for University once your in college, its a good idea to seek careers advisers help. They are there to help and keep you on track.
You online application to University is submitted through UCAS this takes care of Universities paperwork, all offers made are independent to that user only.
It is recommended by UCAS that you start developing your personal statement at a early stay, this would enable you to have your personal statement ready before submitting to UCAS.
Universities would have made there offers to you by end of June, some reply early it depends on the paperwork and results.