Oooh yes totally agree with sussing out where your nearest support group is, and going along once you've started maternity leave. They are usually welcoming to pregnant mums. This is great because you get to see BF happening, which you might not have done much before. You get to hear the advice other people are getting and learn some tips etc and it feels a bit less daunting if you want advice after baby is born.
You don't need to cram in loads and loads and loads of info. I can't even remember what I read before DC1 but I do remember that as soon as I had the baby in my arms I realised that it wouldn't have mattered if I'd memorised every book on breastfeeding - not one single word seemed relevant to this squirmy warm alive thing and I couldn't have put any of that training into practice. This is VERY normal, apparently - that's exactly why midwives have breastfeeding training - even if it's not perfect, it tends to be good to get you going.
Ideally you'll have skin to skin ASAP after birth and it might be that breastfeeding happens here. It doesn't always. I think for me it only did with DC3. DC1 and 2 weren't interested. I seem to remember vaguely thinking "Oh I'm supposed to breastfeed him now!" with DS1 and trying to make him latch on unsuccessfully. Then with DC2 I didn't worry about it and only breastfed him because they wanted to take him off to special care as he was a bit crap at breathing. DC3 I didn't try and amazingly he just magically did it all by himself. DS2 was given bottles in special care, which I worried about. I had no issues latching any of them later on. Don't stress. There's very few things you can't overcome if you have access to good info ASAP.
Once you get home/after that initial first few feeds which generally happen in hospital, then it will be useful to have your book(s), access to a support group - in person is great, online (e.g. mumsnet, facebook) also great. Being able to easily find answers to your questions is helpful. Knowing all of the possible questions you might have and the answers to all of them in advance - impossible, and unnecessary, and probably irrelevant. So don't stress too much about it.
I think it's helpful to know some of the mechanics of how milk is produced, but mainly it's helpful to know where to look for support.
If you have any friends/family members who have breastfed, it's also worth asking them whether they would be happy to be asked questions. I know that I would have been really happy for people to ask me.