I would have to say the biggest worry is adjusting to your new life in the UK. London is completely different from any other city that I have visited. First of all, it's hugely spread out, and vastly populated. You can't just drive to anywhere you want to go. In london, you have to pay a fee to enter the center of the city, that you can pay online, each and every time you enter it. This can be expensive and annoying. Also, if you DO drive in london, be prepared to sit in traffic for hours.
Next is the cost of living. In london, the cost of living is HUGE. Groceries for two people per week I would guestimate cost around £90. Flats are tiny and in london, if you pay less than £800 you are going to be either living with 3/4 other students, or living in a shitbox. Oh that is unless, you want to live on the outskirts of london, but then you'll be taking about an hours underground ride into the center each day. Next, if you don't drive, you'll have to take in consideration how much it costs to use the underground. Each zone costs a different amount, and on a monthly basis if you use it each day, this can be a HEFTY price (£100+) Everything here is expensive, food, rent, parking, etc. Unless you are willing to seriously give up your comforts and live wearing oxfam clothing etc, you will not be able to deal with it.
Next I should mention the political situation here. To put it bluntly, it's not good. The
UK is in so much debt, that it's decided it's going to be like Canada, and cut so much from the budget that middle class people will basically be living off nothing. The only difference (but an important one) is that this WORKED for the canadian government because we were experiencing growth with people moving into canada and the fact that we as canadians have/had ridiculous amounts of resources. This is NOT the case for the overpopulated first-third world britain.
If you are thinking of coming over to study, be prepared to pay a huge new fee implemented by the universities because the government cut their funding of oooh um £9,000 pounds per year. That is a huge fee, and to be honest, in a role reversal, when i came here, I graduated from an accredited college, and they viewed my skills as A level. (that would be like OAC level in canada) so, I would imagine, that if you did study here, it would not be very benificial to go back to canada with your Upper 2nd degree in sociology.
I could seriously go on about how lucky you are to live in canada. I would suggest a visit to london to see the main attractions because some are quite good, but to live here, is a completely different story.