No, by no means are you too late to get into architecture. Your A-Level choices are not necessarily conventional, but architecture is one of the few courses that you can enter with just about any sort of academic background. In fact, History and Geography are excellent and relevant subjects (often mentioned as desired even though most applicants take the Maths/Physics/Art route), and if the history/theory or social/'people' aspects of architecture particularly interest you, certain courses have more of an emphasis on this and you may well be at an advantage with said A-levels. Politics too is to an extent relevant, with Chemistry being the only wild-card (but a hard science which will be respected nonetheless). Let me also mention that, as far as I know, there are only two architecture courses in the country that have specific A-Level requirements (not just desired but are actually required), which are Bath and Strathclyde who ask for either Maths or Physics, so these would be the only two to avoid when it comes to applying. Again, as far as I know, Art is not a 'required' subject at any university. So in terms of 'not having relevant subjects' (which in fact are definitely or somewhat relevant), you're fine.
However, what you absolutely do need is a portfolio. If you intend on applying to UCL, generally considered *the* school for creative/conceptual/arty architecture, and other top courses such as, for example, Cambridge, Sheffield, Cardiff, Nottingham, and Glasgow, you will be required to provide a portfolio. A portfolio for these courses needs to be at the very least better-than-decent to be considered, and it's entirely possible to produce an excellent portfolio without having done GCSE or A-Level Art. Would you say you're a good drawer, or is it an interest and nothing more? If it's the latter, you'll need to practice your drawing skills as drawings should make up the majority of your portfolio (there are video tutorials and even books to help with this, but the best method is practicing by lots of sketching). Even if you consider yourself a fairly skilled drawer, it'll take a lot of time to produce good enough pieces and to compile them into a portfolio, so it's best to start sooner rather than later.
To reiterate, no it's not too late to get into architecture, your A-levels are perfectly suitable, and you will need a good portfolio which will take a lot of time and practice to put together but is very much possible.
Having only just gone through the application process, I'm happy to give more specific advice if you need it. Hope that helps