It varies from subject to subject. Some coordinators (or lecturers) don't set tutorials as a requirement, while others expect you to show up to all of them. Accounting for Business in 2008 (not sure about 2009/2010) made tutorials optional, whereas Managing People and Organisations made all tutorials 'mandatory'. Even when you're expected to show up to all tutorials, you can often get away with 2 or 3 missed lessons.
That aside, you're unlikely to fail if you don't show up, but they do sometimes take tutorial attendance into account when you're a borderline fail/pass... or at least they say they do.