Good first choice
Errm, that's a difficult question! My interpretation is that psychology as a degree sort of intersects the science and arts in that you're learning about SCIENCE, things based on the scientific method. In particular, at bristol the focus is on experimental psychology (which is a good thing!), meaning that the psychology is driven by hypotheses and research questions, rather than more exploratory work sometimes found in qualitative work (although that can be hypothesis-driven too). And, unlike other science subjects, you do argumentative essay writing, so you hone your writing skills. Also, again unlike some other science subjects, you learn stats, which is really useful for a lot of jobs - in and out of research.
Specifically at bristol, in first year you do multiple choice exams, essays and lab reports. In second year you do essay exams, essays, lab reports, and group seminars. In third year you do essay exams, essays, individual seminars, and a dissertation based on a research project.
I wouldn't say it is that difficult... there are a couple others Bristol psych students on TSR who you might get a different opinion from
A lot of people hate stats but it's not that difficult, it's just more numbers-y than people might be used to from A-level psychology. They also start stats at a very basic level (i.e. they don't assume you know anything about it beforehand) and there are practical lab sessions where phd students and a lecturer help you with the lab reports and statistical analysis while you work on a computer.
Do you know what you want to do after your degree? It's okay if you don't, I just might be able to give you more specific details if so