I'm not sure in the UK, but in Australia we don't use those phrases either.
At university, we just name the year. So, freshman = first year. If it's your final year of study, then you're a "final year student". Pretty simple, hey?
We don't use "junior", and "senior" applies to the last year of high school. Again, other years are defined by number: year 9, year 11...
I'd consider freshman, sophmore, etc particularly American. :)