It only takes a minute to write to your MP. Your letter might be the one that makes all the difference. Ask your MP to support a People's Vote on the final deal or ask your MP to support a proposal to revoke Article 50.
If you want a response then it is best to do it by post. They receive '00s of emails a day so your email is less noticed than a letter.
Always start your letter/email with "As your constituent..." as this should guarantee a reply from them and will make them take more notice. Always be polite and give them a reason to support your stance. Always ask a question if you want them to respond.
If you do not know who your MP is you can find out by entering your post code into the parliament website