Neighbours DIY at 10.30pm

10.30 pm was unreasonable. If it happens again you could politely invite one of them your side of the wall while the other one drills/hammers.
They may not have realised how much it would disturb you.

It sounds awful! Maybe they're not aware of how loud it is? You could drop it into the conversation the next time that they seem to have a lot to do as you could hear them working hard, that kind of thing. If it was a once off, then I wouldn't complain, but if it happens regularly then maybe you should complain. It does leave you open to a counter complaint if your dgc are noisy though.

Thank you- we would have invited them round when they moved in but with pandemic it’s a bit difficult. We have had numerous chats over the garden fence/ out the front and they seem quite friendly- they even showed concern for our old (deaf!) border terrier with all the firework noise! Hopefully it will be a one off as I hate complaining, especially when sometimes I’d hate to live next door to us! Lol.

I would be horrified by what you describe. Could you put a card through their door to welcome them & invite round for a cup of tea?
That way you'll get to know what they're up to indoors & can talk about your energetic grandchild.
An exchange of information might help towards resolution? Hopefully, once they're sorted and settled the drilling/DIY will abate.
I do sympathise with you. I feel blessed that the young couple & new baby, joined onto my house, are very very quiet. Just as I am.
Best wishes .... I feel your pain.