Sorry to hear of the issue.
I don't see it as a problem if you propose that to them. Ultimately, they are causing a "nuisance" which in legal terms means their conduct is affecting the enjoyment of your property.
You say this is a block of flats so the freeholder needs to employ reasonably competent contractors to work on the building.
You may make more progress with a law firm - if you write to them yourself they will know you have no lawyer yet and they may not entertain any offers of compensation.
You could ask the local council for their thoughts on this - in case there are environmental health issues too.
The other option is contact your freeholder or management company and ask them for compensation for the disruption - you could apply to the First Tier Property Tribunal if the management company or freeholder are not doing a good enough job.
If you would like a lawyer to deal with this, the Law Society site has a useful search facility as follows : https://solicitors.lawsociety.org.uk
Alternatively, you can try these firms for legal representation (they are a charity who connect you to pro bono lawyers who do not charge you, assuming you meet their eligibility criteria) :
https://www.lawworks.org.uk/ or /www.nationalprobonocentre.org.uk/finding-legal-help/
Here is another: https://www.lawcentres.org.uk