I took aciclovir during both pregnancies and have two very normal children. I know that's only anecdotal, but it was ok!
I was given a preventative dose from 37 weeks with my first.
With my second, I had an outbreak at 34 weeks, so I rang and asked for a preventative dose, but the GP panicked and was like "No, I can't give it to you... I need to talk to the consultant at the hospital." She was then in a total panic that I should have disclosed it and would be consultant led and wouldn't be allowed to birth naturally!! I said to her, my outbreak is on my buttock, it's not actually on my genitals, but it makes me very uncomfortable thinking I could have active lesions during childbirth. She rang the hospital, who basically told her to calm down ;-) Told her that actually, because it was on my buttock, there was no reason to need a preventative course - or a course to treat the outbreak - either, so I could just ride it out! I was then even more cross because I took it when I was pregnant before and my 5 year old is normal, happy, healthy etc. I also said if I feel an outbreak coming and take the aciclovir quick enough, it goes away pretty quickly. Without drugs, it can linger for weeks, which makes me uncomfortable. Especially when due to give birth.
She then agreed that she would prescribe me a course, that I would keep handy and if I felt that itch from 37/38 weeks, I would take the course. That just made me feel a lot better about it all.
Although I then found this AMAZING invention - it's called Herpotherm and looks like a lipstick. You then basically burn your blister with it. Sounds awful - hurts for 10 seconds. And it reduces the inflammation, itch and outbreak. Genuinely since using that, I've rarely needed to use aciclovir, so I highly recommend it.
My usual dose is 200mg 5x a day for 5 days... in total, I take 5000mg in a course. Yours is 4800mg, so although yours seems way higher, it's no more in total, just a more condensed course :-)