Check for planning permission, either here or on your council’s planning portal (Goodle your local authority's name + planning portal).
If planning permission has been granted – Take legal advice. A legal expert is your best bet if planning permission has been granted. Check planning application section for possible areas where the permission could be challenged. Also, contact your local press, ward councillors and MP - the easiest was it to use Write To Them.
If there is no planning permission but work is planned, find out if a section 211 application been made - check your local authority’s planning portal. If a section application 211 was granted but over 2 years ago, it could be invalid, contact planning department or Tree Officer and take legal advice.
If it is nesting season (Feb to August inclusive) and you think there are signs of nesting birds in a tree or trees about to be felled, ask the landowner/contractors for the ecologists’ report and their license which is required to do any work if an active nest is present. If they have no licence or are not co-operating call the police and ask for Wildlife Officer immediately - 999 or 101.
Do you believe it to be a habitat for bats? If yes and work is imminent, call police and ask for Wildlife Officer. If it's not imminent contact your Tree Officer.