SUBJECT: DO THIS
Okay, you've already fucked it up with Leanne, Bollocks to her, she's a bitch anyway and just enjoyed attention off anyone. Don't get too down about it - yes you messed it up mate, but I know FOR A FACT you can get what you want in the future.
In a year or two, you'll meet Natalie. Just act your usual self around her. It's fine.
After another year or so, you'll end up living in a houseshare together. During those late night drunken talks you'll have, tell her the WHOLE TRUTH about yourself. Seriously. She'll probably laugh, and it'll feel horrible, but she is a genuinely nice person, and while she won't understand, she'll empathise. Have the panic attack, it'll pass. They always do. You know this already, no matter how scared you are.
Future you had some great times with her, but they could have been so much better had you been completely honest. Seriously Dave, she could be your wife. Be honest. That's it. BE HONEST TO NATALIE.
Good luck mate, I love you, and she might do as well.