University apllication

Will be starting Sixth Form in September so not familiar with the application process. Would like to know when I'll be asked to start applying, writing my personal statement, invited for interviews ecc.
I just sort of want a time frame, really

You'll need to submit your UCAS application sometime between September and January of your A2s - there is an early deadline in October for Oxbridge/ Medicine/ VetMed etc. but all other courses have an early January equal consideration deadline.
You should probably think about writing your personal statement over your summer holidays after ASs - you don't want to be doing it during autumn term when you need to be focusing on your A levels.
Not many courses have interviews (although most of the early deadline ones do), and their dates will vary a lot. Oxbridge tend to interview in November/ December - but medicine etc. could be any time between October and March.