Local journalists are always looking for stories from the area, and will probably be keen to cover an event like yours that brings together different community groups and your local MP.
The website of your local paper or radio station will probably list an email address you can use to let them know about your event. There might also be phone numbers listed there, which can be a more effective way of getting in touch and not getting lost in a pile of other emails.
As with contacting your MP, you should try to keep your email to the journalist as brief as possible, and make sure your subject line is short and punchy. Consider something like: “Locals plant Family Tree to fight for rights of divided families.”
As for the content of your email, try to follow the format below: