Two bachelor's and a master's

Hello. I am currently on a psychology undergraduate course in the UK. However, I would really like to do a second bachelor's later (physics or maths), possibly in another country due to high fees.
I'm wondering whether it's possible that after doing the second bachelor (and maybe a gap year later or two) I come back to the UK to do masters in psychology. Or can I do master's only in the last subject I studied? And would I still get student finance for that? I am EU student.
If there's anyone with experience in this topic, I would be really grateful for helping me.

You'd definitely be able to do a masters in psychology, the last subject you studied won't stop you. The admissions tutors may be wondering why you've chosen to do a second bachelor in an unrelated subject, so you'd have to prove that you're still interested in psychology on your personal statement.

Funding wise at the moment for doing a postgraduate course in the uk you can get a postgraduate loan as long as long as you don't already have another degree that is masters level above (which neither of your two bachelor degrees would be). You can find information about postgraduate loans here. With you planning to do a masters in a few years though the funding could change and also you'll need to look into what changes are happening for EU students, at the moment you can only get the loan if you have EU settled status.

If you would like to follow a Psychology career in the UK you need extensive work and studying after your first degree just to become chartered. An extra 3,4 or 5 year irrelevant degree in between will make it almost impossible.

Yes, I know that becoming a psychologist would take a lot of work. Do you say that they wouldn't accept me on a masters just because I did something unrelated for a couple of years?

Yes, I know that becoming a psychologist would take a lot of work. Do you say that they wouldn't accept me on a masters just because I did something unrelated for a couple of years?

No, I am saying that it might be a heavy burder for you and/or get distructed along the way, unless you are very dedicated of course.

If you are an E.U. citizen you might consider your options of doing a Psych Masters and recognize your Psychology qualification with the local NARIC. Often 4 and 5 year first degrees allow you to work as a chartered Psychologist in many European countries (they may recognize your 3 BSc + 1 year Psych Masters as such) and then you could seek equivalent accreditation from the BPS sometime in the future. I don't know. Perhaps there is a shorter and much easier route than the traditional UK one (BSc + job placement/Masters/doctorate...).