I messed up my whole UCAS Application

My predicted grades were lowered by my school to a mix of C's and B's (I think it was like BCC). This meant I couldn't apply to the majority of universities I wanted, and had to settle for low-middle tier universities.

However, I recently got the results for my mocks (for which I really tried my hardest) which were ABB, much higher than my predicted grades. This made me realize that if I can get ABB now, there's a good chance I can get it again (or higher) during my real exams. With such grades I could have applied to much better universities, especially those I initially wanted to go to.

I'm considering to do clearing, meaning I'd have to reject all the offers I received and hope I can get a place in one of my desired universities after results day. I've made a big list of all the universities I'd like to try and apply for during clearing (along with some research I did on them) but I'm unsure if I should go through with it.

Is it better to risk getting into a better university I'd actually like to go to, or just keep the 5 guaranteed offers I have? If anyone has been through clearing, I'd appreciate if you could tell me what your experience was like, and whether or not it was worth it.

My course is computer science (which is a popular course which makes me worry that there may be little places available in clearing). Just for extra info, here are the universities I'm considering for clearing:

Birmingham, Nottingham, Edinburgh, Glasgow, Newcastle, East Anglia, Liverpool, Aberdeen, Reading, Aston, Queen Mary, Cardiff and Exeter.

Thank you in advance.

You don't have to risk clearing if you're certain that you will exceed your firm offer, you can then use adjustment which is like clearing but you have 5 days to find somewhere and you don't have to give up any offers so its risk free.

That does sound good, but I'd still have to choose my firm and insurance right? And then when adjustment starts, I'd swap out my firm choice for whatever is available? Just making sure I'm getting everything right.

yes, although you dont have to have an insurance if you dont want to