At the moment the first years have about 22 hours, counting only the compulsory subjects (and tutorials).
31 if you could optional stuff and the time allocated for you to work on your weekly assignments in the computer labs with helpers.
And +3 hours if you want to do a language (otherwise you do "Topics in AI" in your second term).
When it comes to the work load I have to say being at Imperial has suddenly turned me into one of those people who do their work as soon as they get it and hand it in as early as possible... I've always been the complete opposite.
If you organise your work well you can get yourself a few nights a week off without spoiling any grades, (at least in the first term, which is all I've experienced so far).
There aren't many lectures where their material is particularly dull, it's usually the lecturers. Some are amazing, some are boring and tedious.