I'll do my best to give some advice
First, don't give up your future for her (referring to your last comment at staying in Canada). I know how tempting it is to put aside everything for love, but this could be your one chance to secure a certain future (medicine at UCL). If you go against that, you could end up regretting it later and may not be able to start over, and you may even be mad at her for it (subconsciously or not).
What's most important is that you sit down with your girlfriend and figure out some sort of post-university plan. If you're both at university in separate countries, it will feel so hopeless. You'll constantly be asking yourself, "Where is this going?" etc. But if you figure out what's going to happen after university, you'll give yourself hope and something to look forward to. So decide where you two will live after uni. What efforts are you going to put towards being together?
Something that has worked out so well for my boyfriend and I is that he's a night owl. His time zone is 8 hours ahead of mine and for any normal couple, that would give us so little time to speak to each other. But he stays up until 3-5am every night. So I can speak to him anytime from when I wake up to 9pm my time. That's a pretty good deal. Additionally, we're both very computer/online-oriented people. So we enjoy spending a lot of time on the computer, both to talk to each other and to do other things (play games, web browse, etc.). So communicating is very, very easy for us.
Now I'm not necessarily going to tell you to change your sleeping habits or anything, but I'm just throwing it out there for consideration.
In order to help us connect, my boyfriend and I do as much as we can "together" without physically being together. We play games together, we watch movies at the same time and talk about them through a messenger, etc. It's a great way of connecting and interacting without being face to face. It's not as good as the real thing, of course, but it helps us stay close and not feel as helpless
So it certainly is possible to maintain a relationship that far apart for that long (I had a 4 year international LDR before my current one!), but it will be hard every single day. There are things you can do to "numb the pain" and make it easier, but it will never be painless. Though I agree with an above comment that says it will get a bit easier. I'd say that it starts out being very difficult, it'll get better after a while, and then maybe get worse again.. especially around birthdays and anniversaries if you can't be together in person for those.