You can start off by using your postcode on WritetoThem to find your MP. You don’t need to be a UK citizen to do this, but you must be resident in their constituency.
Because the emails are pre-sorted to the correct MP by postcode, s/he knows immediately that the email comes from a constituent.
WritetoThem won’t bombard you with spam, but the website does email you later to ask whether you received a reply. MPs get rated by WritetoThem and they know this, so you may get a speedier response by using this rather than the official House of Commons email.
The website has tips on writing to your MP and will also suggest your next step, if you don’t get a reply.
Suggest that you don’t duplicate information available to the MP in the national media. Your MP has access to that plus reports, briefings, Hansard and a whole lot more.
What your MP doesn’t have, is your story. How the European Union referendum campaign and Leave vote has affected you, your family and your community. The effects which Brexit would or might have.
Those are the sorts of emails which can make a difference.