Gosh people these days really struggle with nuance and compromise, don't they?
OP you sound lovely. When my Neighbours did a big extension, I was pregnant after miscarriage. They didn't stop the work for the 9 months, that would have been ridiculous but they did let me know specific times the noisiest work was going to be carried out and strictly enforced start and end times. Which meant I knew when the noise would be and could avoid a lot of it. It reduced the stress massively for me. If I was ever going to do a big piece of work I'd ask them in advance when would work best for them and try and factor that in with the builders, then I'd let them know when it's ongoing what will be happening and when. It's not rocket science. We both benefit from being decent and some minimal communication.
In a previous house we had truly shitty neighbours who used the noisiest possible equipment - such that our entire house shook - pounding the driveway one bank holiday weekend without bothering to inform us. It was not knowing when it was going to start up again (which was pretty much on and off 8-6 for the entire weekend including the bank hol monday) which was the worst - it was being on edge for the entire weekend. We could have easily made plans to be elsewhere but their lack of basic communication and consideration meant that option was taken away from us. We went out a bit but because we didn't know when it'd end we didn't know when to come back and it was so demoralising to come back at 5.45 and it was still going.
Hopefully the office will be a good compromise but I'd also ask for the child's schedule, also find out what A-levels they want to do and prioritise quieter work right before those GCSE exams (which will be a limited number). Ask the builders if it's possible to do the absolutely, ground shaking, nosiest work when she'll be out having exams. Ask them to strictly stick to start and end times, so the child can plan her revision when it's quieter and isn't stressed when work which was supposed to stop half an hour ago is still ongoing. Communication and some slight compromise.
Ask the builders if they have other jobs, and if so maybe they could do some of those on the days before the A-level subject exams. My experience of builders is that they often have lots of things going on and can accommodate this sort of thing for a day or two. Probably some of them have children who either are sitting or have sat exams and will be keen to help.