I think it's normal for them to just share the workload with the GP. Not good them not getting you your test results though!
I wasn't impressed with the midwife at my booking-in appointment - I didn't get any questions answered, she said the answers would be the info she gave me and then I went home to find the info pack contained a list of questions to ask! Luckily I'll now be seeing a different midwife at the childrens centre near us, and I've already spoken to her on the phone and she seems more with it, lol.
It's annoying when your nearest or preferred hospital is actually out of your PCT area, so the midwives and GPs are connected to a different hospital. I had that option here and the midwives don't seem to know much about the out of area hospital at all! But then, they'd never work there, so not too surprising I suppose. Have you seen if the hospital has a website with info? I found that answered more questions than the midwife could!
I don't think GPs will usually take up all the workload from shared care. One option would be to get a private midwife, but that's pretty expensive and if you are having a hospital birth, then they may only be able to be your birth partner at that hospital, not your main midwife.
The NHS midwives don't seem to spend much time on birth plans (a friend said you get a LOT more support with a private MW), but there's a lot you can research yourself if you like to be prepared (like me!). Dr Miriam Stoppard's book has some excellent advice and the NCT are fab. Maybe see if the NCT have a Working Bumps or Bumps & Babes group near you so you can start going along now, rather than having to wait for your class - the group leaders are great for asking questions and meeting other local mums-to-be who already have kids or have investigated local services saves a lot of time and effort.