A social worker, whatever their field, should have the capacity to attain the situation best for their charges interests quickly, efficiently and with empathy.
I think a starting wage of 26k p.a. is very good looking on paper, especially as a fresh-out-of-uni wage and definitely for a graduate without children or a parter or a mortgage, but personally I don't think the aptitude to be a social worker and I wouldn't enrol when I know I can earn more money doing things I am better at.
You seem to have gotten a bit hung up on the whole regulatory body thing, OP. Can I just say, it doesn't really matter. Yes, you need to know who regulates you, you need to know how the absorption of one body into another changed framework and guidelines, but it's background knowledge.
You should be aware of it and not much more, just as I am aware that my institution is the research department of a larger body but it has no impact on my day to day practice.
I know the book is a sore point by now and no, you shouldn't chuck it. There's probably very good information in there but I wouldn't recommend using it as a reference for your essays nor as a guideline for your practice, when it comes to that.
If you still want to do so and you think the information can still be applied to modern social care, by all means go ahead, but don't be surprised if you are pulled up on it. You should of course cross reference it with modern material but I don't know if that will be enough as the book is so out of date.
I know you said it's core text of your course, do you mean the first print was in 04 and you have a newer edition? That would make more sense.
My advice would be to remember that you are responsible for someone's wellbeing, no matter what field you practice in, so always listen, react appropriately and be empathetic as well as getting the job done.
Anyway, best of luck with the degree 