You must be joking, there is very little legislation for aircraft noise, in fact it is excluded from the noise nuisance act as if it were included your lives would be a lot more difficult. Sure around airprots there are limits, but in open air space they can make as much noise as they like.
Incorrect. Modern helicopters have to comply with noise limits as part of the airworthiness regulations and are issued with a noise certificate.
L&L states that he lives outside the LCZ, by which I presume is meant the London Heathrow Control zone, or London City zone.