Okay, so I know medlink has been and gone, but:
Medlink offers nothing to your application to medicine, I didn't even put it on my UCAS form and I wouldn't advice others to do so because well as seen from this thread it has certain connotations.
Despite that I'm very glad I went. It's at the beginning of your AS year, and what it did was drill into me the importance of good organisation, getting work experience (and consequently by the Easter of my AS year I'd organised lots of placements) and getting the grades. It was an amazing motivator! And generally a good experience.
It also changed my parent's attitudes really, who prior to that had never taken the "I want to do medicine" thing seriously at all and had no idea what it involved.
So for that reason I'd say if you can afford to go -- go. Admittedly my costs were subsidised so I did not pay anywhere near £200 but I know to lots of people that really isn't that much money (or at least to their parents) and if you're fortunate enough to be in that position then why not? If like me, that is a lot of money to you, then I'd think about it more carefully because it does not, despite what they say, add anything to your application in itself. But if you still decided you wanted to go then fair does, I gained a lot from medlink.