I'm not there yet, but from what i've heard not a lot!!!
i think i have about 6hours of lectures a week, plus a 3hour practical every week or every other week (most unis are about the same)
then most unis require you to do another 2 modules from a different subject so thats another 2 hours of lectures. there are also tutorials, but dont know how regularly they are!
independently theres also lab reports every week or every other week and some reading (apparently most people don't really bother with that though! guess depends on the uni to how important it is to do!)
think most unis are similarish as nottingham only has lectures 3 days a week (and not many of them then!!!) and i know manchester has a few days off a week as well!
sounds like we picked a good degree!!! (suspect the 2nd and 3rd years may require a bit more work though dammit! hehe)