I have GBS and had IV antibiotics in my last labour (DD now 2.5).
They give you the abs via a venflon rather than a drip so you can still move around, although your use of that hand is rather impaired.
Unless you have other risk factors (see GBS website) the use of abs should be "considered". It is only specifically recommended if you have other risk factors.
As far as I can tell, there seems to be a policy of encouraging abs with a positive test result (based on the unreliable NHS test) even if there are any other risk factors. This goes against the national guidelines on GBS and abs.
Apparently there is recent research (don't have refs, sorry) that waterbirth reduces the chance of the baby becoming infected.
You need to get a copy of the hospital's protocol on GBS. They should have alert stickers (ours are bright green) that go all over your notes. DD and I stayed in for 48 hours post delivery, I think, to have her bp and temp monitored.
Our hospital also won't let you use the midwife-led unit - you have to be in the delivery suite. I'm pregnant again and I'm thinking about not having the abs unless I have an additional risk factor. I'll have the private test late on in pregnancy too. ALso, if I end up having the abs I'm going to try my best to be allowed to use the midwife-led unit and to have the venflon removed and re-sited if necessary. I found it hard to grip things, weight bear on my arm etc with the venflon in.
Sorry, rather disjointed but I'm wrestling with the children!