Firstly, try talking to them! It’s good to open up a good communication flow and one in three people have found that this solved any problems immediately.
Something that is key to remember when approaching them is that although you may be frustrated, it is important to remain calm and reasonable rather than being confrontational. It is better to talk things through and explain the situation more clearly, they may not have even realised they were causing a nuisance!
If your neighbour is a tenant, you can always contact their landlord and explain the issue. If you are a tenant living in a rented property, then you can also contact your landlord or housing association and express your issue. Lettings agents and housing associations will have a formal complaint process in place to deal with any issues.
If the problem is a more serious, continuing issue then it is worth making a note of dates and timings of the disruptions which can be used in future if you need to go to the council or even the police.
When approaching them, if you feel intimidated or apprehensive about talking to your neighbour due to anti-social behaviour then you should contact your local authority. UK legislation allows for councils to issue a warning notice to any noise complaints that is louder than a permitted level between the hours of 11pm and 7am.
Remember that they are human too! Being friendly and approachable, and remember to be reasonable as it could have been an honest mistake. Remember that friendly neighbours are a blessing!