Stop worrying!
All sorts of people get letters from the council about (alleged) 'noise pollution'. My friend is 77 years old. She's a 'model citizen', whom many people turn to for help and advice. She's also as 'law abiding' as it's possible to be. (She'd go into a panic if someone said that she might have accidentally dropped a piece of litter!). But, a few months ago, an un-named fellow-resident of her block of flats reported her to the council because of the (alleged) "excessive noise" coming from her flat. For a while she really let it get her down but now (while she's still trying to reduce the volume on her TV a bit, and also trying to stop her dogs from barking too much) she's decided to largely ignore her critic(s) and to simply get on with living her life.
If a 'totally respectable' lady of 77 years can get a complaint from the council (and she's not even a council tenant!), anyone can!
If there are ways that you can reduce the noise level from your property then, obviously (in the interests of local harmony), you'd be wise to do so. However the old motto of "Don't let the b@stards grind you down" would seem to apply here!
I see from your profile that you're new to this site. If you keep on posting you'll probably find that we're a strange lot around here but we do try to help as well ;-)
All the best,
Chris