I haven't taken a social work degree in the UK, but did a BA (Hons) Health and Social Care part time to formalise my understanding of the UK welfare state system once here (and here for some years already).
The biggest differences between social work courses in the UK and Canada are: more UK placement hours and the honours degree system in the UK means no wider foundation on which to base practice: e.g. psychology and development, if working with children, drug and alcohol courses, courses regarding disability, gender identity, class and ethnicity, for example.
I'd really consider where you want to practice, both geographically i.e. which country and field wise. I think inter-country transferability between the US and UK may be more challenging, so that is worth investigation.
http://www.cswe.org/CentersInitiatives/22207.aspxYou also would be likely paying international fees and no bursary. Some courses may not allow international students as they may all be for home students.
http://www.nhsbsa.nhs.uk/Students/835.aspx Hope that helps.