Amy, we're about the same age, so I share some of your life experience to know that you've been through things that make you just a little more savvy about your decisions. And yet...
"Internet love" is going to bowl you away. It's going to be a love you have never known before. I don't care who the guy is. It has nothing to do with the guy, it's all to do with a very strong medium, a way to 'meet' people. You're going to meet this man in person and so convinced you will be that he is THE ONE that you will overlook the things that normally you'd not give the time of day for. He's a smoker/you're not. He goes out with his mates several times a week/you're an at-home sort of person. He's footie crazy. He only washes once a week. He leaves the toilet seat up. Oh man...the list is endless. And don't overlook your age difference. You might have loved Herman's Hermits and the Kinks, but he was into a Flock of Seagulls and Boy George.
You've already decided you'll have sex. You're already committed to marriage. You've mentally moved to the UK. Making these sort of decisions without having met him is going to make it tough to say 'no' if things don't work out.
That's the caution I want to give. I certainly don't deny the sincerity of your feelings. I just recall all the pain I personally have been through by making decisions ahead of time and then feeling pushed to a point I couldn't back out. This is, of course, all before my own Brit husband...I actually met him in person and then fell head-over-heals. You see, I'm an Anglophile...I love England, always have been drawn to it, the culture, the words, the beauty, history, accents...everything. I came to see the country, and only then did I meet the man of my dreams.