For legal reasons in the UK, I need to submit my physical address on?
The problem is that if they are asking for proof of legal residence, what you are doing is likely illegal. I was in the same position and the challenge of beating the system was a source of entertainment. I needed a physical address to get my passport sent to me. They knew I was in the UAE and had policies to not send sensitive documents to box numbers If you check carefully you may find that the thing you want to do is not possible of you are resident overseas. I ended up using a lawyer in the UK to act for me just so I could send the passport to them and they forwarded it to me. Which lawyer you need depends on what you want to achieve. I succeeded with an immigration lawyer but you might have different issues.