Plymouth university may not be able to offer you accomadation in halls. In previous years it hasn't offered halls accomadation to students applying through clearing. However, Plymouth does have some private halls of residences which you would be eligable to live in. Is this something you have considered?
If you do the two years at college, plus the top up year, you would get a full BSc (hons) provided you got good enough grades.. However, I know a few people who followed this route (via a different partner college) and were only allowed entry into second year, rather than third as the university didn't feel the standard of work at the partner college was high enough. This means getting their BSc will take them 4 years. It's not a major issue, as you can still get student finance, but it means you won't get finance if you fail and need to repeat a year.
You would be doing university standard work, and it is likely you would follow a more "university" style of teaching, but because it is run in a college, it's likely that it will end up being a middle ground between being at college and doing a full degree. This may be a good thing for you, as during the first two years of your degree you would get a bit more support.