How important are AS levels?

I finished my AS exams last week as am just wondering how important they are.

In my school they are only used to decide whether your allowed to return for year 13. Even then you have to get a minimum of 3 Ds to get into year 13.

I am 100% sure I can get into year 13 so that isn’t my problem.

However I don’t think I have done very well in my exams. I’m guessing I got mostly Cs and maybe a B or D.

I really didn’t take my AS levels seriously so I didn’t revise that much.

How will this affect getting into university. I am going to try really hard during A levels and I’m sure I can push up my grades to As.

If I get good A levels, do AS grades matter.

Also another problem for me is that my school predicts my grades based on my AS results. This probably means I’m going to have to take a gap year as I do t want to go to the universities I can get into with bad predicted grades.

So if I do get bad predicted grades and good real A levels, how would I go about getting into the universities I want to go like LSE or UCL?

Thanks in advance for answering.
Any comments would be helpful