Clinical Psychology

Can't answer all your questions but I'll answer what I can, I'm in my second year of a psychology undergrad degree.

To become a clinical psychologist you need to do postgraduate qualifications - in the form of a clinical psychology doctorate (DclinPsy) which takes 3 years to complete. To get onto the doctoral programme you need to have an undergraduate degree accredited by the BPS (British Psychological Society) which is usually 3yrs (4 if you have a placement year), after which a majority (it is not compulsory) will do a masters degree (usually 1year), the Doctorate also requires at least a year of doing relevant work experience (paid) So, at the very minimum you're looking at 7years to become a psychologist, not including the year after finishing the Doctorate you become a 'trainee' of sorts. However, it's important to note that most people applying for the Doctorate will have many more years of experience than just one.

I can only speak for undergraduate psychology but there's a decent amount of biology in certain units (Biopsychology/neuropsychology), you don't do straight maths though, maths comes in the form of statistics, however you use a computer programme (SPSS or Excel usually) to do calculations and such

Thank you that honestly helped a lot. How many years of experience would I roughly need to get hired as a clinical psychologist in the NHS?

(just a note I'm no expert on this so idk if this info is 100% correct, feel free to correct me)

Assuming you mean after you're qualified? The majority of the Doctorate is placement based, so you'll already be working in the NHS in order to qualify in the first place. You don't really need experience after you've don't the DclinPsy, aside from your trainee year after you graduate (As far as I'm aware anyway)