I'm doing further, legal studies, english and I completed psychology last year.
Further: I've found it pretty easy. I wasn't quite smart enough for methods, but it's not like I've ever been bad at maths. I didn't do much work last year (for units 1&2 subject) but managed mid eighties/ninties, the lowest mark I got in unit 2 was 82%. This year I've worked a lot harder (by doing all the questions in the exercises, working ahead of the class, etc) and managed a 95% in the first SAC relatively easily. It's just about doing all the work you can, because doing questions is really what helps you. The course varies from school to school because you get different modules.
Legal Studies: It's pretty content heavy, but if you work through it it's not bad. I worry that my teacher is too easy of a marker, though, so I'm not sure how people from other schools find it. It's generally a pretty fascinating subject though! It's widened my understand a lot, so I enjoy studying it.
English: Not going to lie, English is hard and rather competitive. The best thing you can do for yourself is read a lot, and write practise essays before each SAC. Apparently the exam will never give you too difficult a prompt though, which is a plus.
Pyschology: I did it last year, and I was a slacker. I got decent marks (B for unit 3, A for unit 4), but I didn't study actively, usually only for SACs, and left my exam preparation for the three weeks beforehand. I honestly didn't make the most of it as a 3/4 subject, something I regret now. The fact that it was the only important exam I had to study for was the only reason I managed to get a 35 study score. My advice to you, if you choose psych, is to make the most of it; it's genuinely a fascinating subject so studying for it will actually be pretty enjoyable.