I'm also a gap year student with an offer for Exeter Cornwall for English, though I haven't accepted yet.
I think it's quieter - not so much night life club wise, but there are plenty of nice pubs and they regularly hold events at the Stannary or on the beach, or so I was told by students I met on open day.
There are still plenty of things to do, but it's just not as hectic as a city - it depends what you're looking for really. They do have student house parties regularly from what I've heard and seen on FB (I know several people who go there and believe me, they do party) and everyone I met on open day seemed very sociable and chatty, so I don't think it'd be too quiet, maybe just quieter than in a city.
Accommodation wise, it's self catered and you either live at Glasney Student Village which is on campus, or at The Sidings, which are a short walk away and literally right next to the Penryn train station, so transport links are very good. It's a bit less noisy at The Sidings apparently, but the students living there do still socialise and go up to the main campus regularly for events. The accommodation is quite pricey but seemed very safe and modern, both in Glasney and The Sidings.
I'm a fairly sociable person, so if I do choose to go there then there'll be at least one person up for nights out!