Colleges at Cambridge and at Oxford are naturally cautious about what they say to people who are thinking of applying but have not yet applied. No college can give you the sort of reassurance which you may be seeking in advance of an application, and nor can anyone on this Forum. Cambridge colleges will assess an application, if you make one, on the basis of your overall academic history and potential, with regard to any subject-relevant aptitude test which you take and how well you do at interview. They will be assessing whether you are teachable within the Cambridge teaching system.
In very broad and very general terms, leading universities may prefer that a candidate's sixth form qualifications were obtained all in one go, but every case will be considered on its individual merits. My nephew fluffed his A levels, did this and that for several years, and then obtained good A levels and went to Oxford at the age of 23. But that's just one example, and your present circumstances are not the same as his were.
You can but try. Put together a good overall application, show your achieved grades, and do as well as you can in any relevant aptitude test. Maybe then look at youtube videos about interview preparation (preferably the ones made by Oxbridge Dons, not by students), and give it a go. I suggest that that you also apply to a range of other universities, because, as you may already know, most people who apply to Cambridge don't get in, and the same can be said of other highly rated universities in London and elsewhere.
Good luck!