Hi, there. Once u got accepted, yr status is PhD candidate. Then after 1 or 2 years, when u pass the Qualify Examination, you can become PhD student.If u fail, u may get a master or nothing. Finally, when u finish yr PhD thesis and oral defense, you can be called a PhD. This is the system in US and most other universities. There are some difference in UK system. Plz check by yrself. Good luck.