Canada to ENGLAND (Residence)

Hey! So me and my best friend have been making a plan to move down to England for a few years. As soon as we graduate College we're going to make the massive leap and do it (We've been saving up, and all that fun jazz)

But in the back of my mind, I'm always stressing about the diabetes situation.. I will be leaving my Doctor's behind, but thats not a huge deal, as they'll be giving me all new doctors when I turn 18 next years anyways :p what I'm mainly concerned about is the COST OF HEALTHCARE. I've read on several sources, that like Canada (where I'm currently living) the Healthcare in the UK is FREE.. But what does that mean for me?

Basically what I'm asking. Is there anyone who recently moved to the UK, or lives there? and how much of HC is covered? Keep in mind, I dont plan on permanently residing in England. Even though, I do plan on staying for 3-4 years... Would I still be accepted for Free Healthcare?

Please Help me!

Lots of love Xx