At most UK universities, students do exams or assessments every year; at the end, these marks are averaged into a final grade. The only exception
AFAIK is Oxford, where most students take two sets of exams, and the final set of results is averaged to get a final grade.
All UK universities will give students transcripts if requested, but they might have a different name, e.g. 'record of examination results' or something like that. They will usually be percentages, not letter grades. However, you can ask universities to provide a brief explanation of how they award percentages, and I'm sure US universities would be able to translate these into letter grades.
I imagine that a second year module would be equivalent to Junior year, but that's probably something to email the programme administrators at King's about.