First of all congratulations for your offers!
I think that obtaining a distinction is doable if you work seriously enough.
I was enroled in the MSc EME at LSE, and throughout the year thought I would never pass the program. I did not work much or prepare classes. Then I started preparing for the exams, worked hard, and ended with a merit, missing the distinction by two percent.
The 'morale' of my story is that I think most of the sudents in such programs have the ability to get very good grades, if only they work hard/seriously enough.
Regarding your interests in labour and applied microeconometrics, UCL is the place to go!