So, the last thread filled up so quickly, I barely got a chance to reply to most people. I really wasn't expecting that but I was reassured by the vast majority of replies.
I always like to see a follow up so I'll post this for anyone who's interested.
Anyway, the neighbours turned down our offer of the office space for now but did say the may take us up on it in the coming weeks.
We now have issues on the other side as neighbour there has claimed that knocking our garden wall did damage to his conservatory window. Thankfully, our builders took photos of said conservatory before they knocked the wall as they've clearly been around the block a few times and cracks were there before.
Pretty sure we'll be social pariahs by the time we move in. Such a pity!
I will, of course, be delivering presents to both sets of neighbours in recognition of the hardship they're facing at the moment.