Original post by doctorwhofan98A2 is definitely harder than AS in most subjects, though I actually found A2 Lit easier, so it might depend on how you work etc. You'll probably be fine if you don't leave stuff till the last minute - for example, in A2 History, we had to do coursework, which was entirely independent research and therefore completely daunting. I did procrastinate a bit, but I left enough time, so the daunting task became significantly less daunting and everything turned out ok. Meanwhile, a lot of other people left it till literally the last day, making the task impossible, and came out with bad grades. So there is a jump to A2, but as long as you're aware of it, and plan appropriately, you'll be fine, and the same applies to exams - they may seem daunting, with more to learn and a more difficult technique, but plan to go over topics and revise early and you'll be ok.
As for university, think carefully about your choices. I messed up in that regard - I only visited top unis last summer as I wrongly presumed I'd get 4 As. I instead got AAABB, which led to last minute application changes. Ultimately I'm happy with my firm, but I really don't like my insurance (too late to change as I only visited after applying!), and I regret not applying to my dream uni - I'd presumed I wouldn't get in, when I would've actually had a decent chance. Visit everywhere, have a backup you like, and have an optimistic choice! Also, start on your personal statement early, and get advice from as many people as you can... but don't be afraid to ignore what you think is bad advice!
And a final couple of tips - don't panic, no matter how daunting/scary year 13 can be, make good use of your frees (the year will fly by - take advantage of the time), and don't don't work too many hours if you have a job.