Architecture vs Architectural and indisciplinary studies personal statement

Have you spoken to UCL about this? They might be happy to reassure you that an architecture ps is fine.
Have you looked into Goldsmiths design BA? It’s quite unusual to apply for architecture degrees with zero intention to become an architect. What is it that you hope to use your degree for?

Yes I have contacted UCL and they said I could include something that expands out of architecture into another similar interest (most likely to another indisciplinary subject) As for why I’m taking this degree, yes I do enjoy the subject, however I want to get into UI/UX design. This field uses very similar theoretical fundamentals to architecture, it’s just the practical applications that are different. It is also common for those in architecture who are looking for a different field, to go into UI/UX. Therefore choosing architectural and indisciplinary studies would suit me perfectly.

Yes I have contacted UCL and they said I could include something that expands out of architecture into another similar interest (most likely to another indisciplinary subject) As for why I’m taking this degree, yes I do enjoy the subject, however I want to get into UI/UX design. This field uses very similar theoretical fundamentals to architecture, it’s just the practical applications that are different. It is also common for those in architecture who are looking for a different field, to go into UI/UX. Therefore choosing architectural and indisciplinary studies would suit me perfectly.

Right so it is common for people switching from architecture to go into UI/UX, but that's only in the sense that if you want to leave the architectural profession UI/UX is a common choice to pivot into (because it tends to be very well paid).
But the switch is not easy. I did architecture at uni and have seen some of my peers attempt a career change into UI/UX. some found jobs pretty quickly, but others spent a long time reskilling and doing unpaid work for their portfolio before finding anything (if they did at all).
The reskilling is also quite significant - working in UX requires a lot of skills and knowledge of concepts that architecture school simply will not teach you. For example, information architecture, wireframing, user testing, use of software like Figma, typography, any of the very useful UI/UX design principles on this page, and so on. Not to mention the fact that you'll need to build a portfolio of UI/UX work separate from whatever architectural projects you'll do at uni.
i'm not an expert, but I would imagine something like an Interaction Design degree might be more suited for getting into the UI/UX industry; or a Human-Computer Interaction Master's degree preceded by CompSci, Psychology or whatever other degree would fulfil the entry requirements.
of course, if you want to do architecture at uni then go for it, it just probably won't be much help in getting a UI/UX job

I know that an architecture degree by itself won’t help me much in getting a job in that field, which is why in my gap year I’m planning to learn UI/UX and related skills anyways, and build a portfolio from there (doing free work, freelancing ect). Of course the advantage of this is if I change my mind at some point I can always go back and continue the architecture path after graduation.