The best first step is to speak to your neighbour directly and see if the dispute can be calmly solved face-to-face. Go into the conversation knowing your rights and openly voice your feelings and concerns to them.
Should the issue persist or the conversation turn sour, you can let them know you intend to get help from the council. Although awkward, it's important to voice concerns as soon as they arise so that issues can be resolved before they worsen.