I tested positive for GBS and chose to have antibiotics during labour with DD as a precautionary measure. You can read more about GBS here
I read about GBS extensively, as I realised that having the antibiotics would compromise my preferred birth-plan (minimal intervention, and preferably waterbirth), but was still unprepared for certain aspects.
For example my waters broke prior to having any contactions. I phoned the hosp and they asked me to come in asap. On arrival they examined me and told me that they wanted to start an induction. I was really shocked by that. I knew that prolonged rupture of membranes can pose a risk to the baby, but I thought they would just want to monitor me, or perhaps start giving me antibiotics.
Anyway, I declined the induction and asked to be given a dose of ABs. I then discharged myself from the hosp and went home to see if I could get things started on my own. A few hours later the contrax had started and I returned to the hosp. They continued with the doses of ABs for about 12 hours. I also had to have a strap-on monitor thingy, and I wasn't allowed a waterbirth. I did feel somewhat 'hassled' by the hospital to speed things up. Eventually I gave in and allowed an augmentation and epidural.
With DS I was more prepared. Spoke to the midwives and hospital in advance of birth to try to negotiate waterbirth PLUS IV antibiotics. They were very understanding (it was a diff hosp btw), and were prepared to help me as much as poss. In the end the labour was so fast that I didn;t have time for the required dosage of ABs...or a waterbirth lol!
Anyway, the point of this ramble is that your friend would be advised to speak to the hosp/birth centre and make sure that her plans won;t be unexpectedly scuppered (it's horrid whe you feel wrong-footed during labour). The IV antibiotics are not a big deal. She can ask them to put the drip into a more convenient vein (it's a bit annoying on the back of the hand, better on the wrist or arm). They take about 20 mins to flush through and she'll prob need them every four hours. She might want to take some probiotics with her for afterwards. There are many alternatives to penicillin.
She may of course decide not to have the ABs in which case she should remember that about 1 in 4 women have the bacteria and the vast majority have no probs. DS was monitored every 4 hours after the birth for 48 hours (as he hadn't received the required ABs during labour). I wasn't worried about him, but I felt glad that I was aware of the potential issue.