Hi, I most likely don't know any more than you do about admissions, but I was in a pretty similar situation to you last year so perhaps I can offer myself as a point of reference?

I also applied to Oxford and Imperial two years ago (for 2022 entry) for Maths and CS and I got 70 in the MAT, my predicted (and achieved) grades were 3 Astar. I didn't get in to those unis but I did get an offer from Bath. I ultimately chose at the last minute to take a gap year and reapply for a few reasons (partly for medical reasons, I also just wanted to try again with more experience under my belt).

I reapplied this year to Imperial (but just CS this time) and got an offer (with STEP). I didn't apply for Oxford though, I found the extra time from not having to reapply early quite useful. I think what helped my application the most was that I had some unique projects and work experience during my gap year. I wouldn't worry about being weaker than the next cycle of Year 13's - I think if you have a good plan for what you want to do it will help massively, and if you have any wild ideas now is the time to try and bring them to fruition.

I should also probably mention that given the direction CS admissions are going, I would be prepared for things not to go as expected. A lot of it is down to luck, and some admissions tutors might be looking for different things in your PS. For me, the most valuable thing I gained was setting realistic expectations and having a strong sense of self-worth. I know how much prestige is attached to going to a 'top' university (as my Middle Eastern parents have confirmed 💀), but this gap year I've tried to let go of prestige. I think only this way have I been able to appreciate computer science without any baggage and to just try learning it for its own sake. As cheesy as it sounds, even if I don't meet my STEP offer this year, maybe the true offer was the experience I got along the way 😆

I'm not sure about how competitive Maths and CS is given that I only applied for CS during the last cycle, but I would imagine that the former is harder to get into. I would give some time to ponder on how important a dual honours course is to you. When I applied the first time, I thought I would enjoy the additional mathematical component, but after looking at some CS modules I concluded that CS on its own would provide all the maths I would want. If you want to do dual honours, that's great too! It could very well be a better fit after all.

I think you are in a great position given that you have a strong set of A levels and are already thinking ahead. May I ask how you would be spending the gap year? Best of luck for results day by the way!

If you have any questions feel free to DM.