Unfortunately, unless you are going to go to a lot of expense putting up sound insulation on your party walls, and of bricking up the wall in your loft, the only real option you've got, is to go and talk to them (they may not realise the problems they are causing) as their behaviour come under the anti social category, and they are not allowed to carry on in a manner that things can be heard outside of their property.
If they are not prepared to be more considerate, then you can warn them that you've got no other option than to turn your music and tv up to drown out the noise, but you'll turn it down as soon as the kids go to bed.
As to a noise complaint, you just ring the council offices, and tell them of the problem, and they'll send a letter to your neighbour, and send you a form to keep track of the noise.