Most aircraft noise is exempt from the statutory nuisance regime and aviation policy and regulation is largely controlled by the UK Government (princially through the Civil Aviation Authority). You can still register a complaint with your local authority though as this will help them measure trends in interest and concern.
Some local authorities have taken legal action to prevent expansion or reduce number of flights (usually by way of injunction).
Aircraft noise from the aircraft themselves has reduced over the years as technological advancements in aerodynamics and engine design have advanced. However, the number of international flights has boomed alongside globalisation.
Military aviation is controlled by the Ministry of Defence who can be contacted through the MoD Complaints and Enquiries Unit.
Further information on civil aviation can be found on the CAA site here.
Other useful websites are airportwatch.org.uk and www.hacan.org.uk .