Is it possible to change unis after a year to either progress straight into second year or, if there's a considerable difference between the unis, repeat first year? As I've good grades but I didn't feel confident enough to apply this year to more prestigious unis, with say a successful year studying elsewhere, would top universities consider taking me then or is this just something they don't consider?
The short answer is yes, it may be possible, but it is very case by case depending on the course. Generally speaking, the more competitive the course, the less likely they are to be welcoming to year 2 entry.