In recent years complaints about fireworks have increased dramatically.  Previously it was only possible to buy fireworks in the run up to 5th November.  However, many vendors now hold stocks until the new year, especially since the millennium; so the firework "season" now lasts two months or so, as opposed to two weeks.

Firstly, there are no specific UK regulations to cover noise from fireworks and if you are disturbed and wish to have action taken, it is a matter of pressing into service the normal statutory nuisance legislation.  It is unlikely that a Court would accept that a single firework party was a nuisance, unless possibly it disturbed most of a night's sleep [23:00 - 07:00 hours], but it may be possible to prove that regular events at the same venue, are a nuisance; it may even be possible to get a Court to accept that collective events in an area are a nuisance; the biggest problem being finding the person responsible for each firework event so that they can be enjoined in an action.

Probably the most relevant assessment methodology is the WHO guidance with regard to instantaneous loud noises at night.

If you are considering having fireworks at an event and are concerned about disturbing neighbours, a reasonable starting point would be to avoid the noise night (23:00 to 07:00 hours) unless it is New Years Eve!, try and keep it short and as early in the evening as possible; if you think that disturbance is inevitable, it is also a good idea to forewarn residents by means of a note through the door, to tell them the start and end times and stick to them.

Hope these sparse comments help.