In general I think 40% is a pass. Our system is technically you must get 40% on the exam in all core modules, but if your assignment work and overall year score are high enough then they may reconsider. In the case you get less than this then you have to resit in the summer. In the case you get less than 30% you are reccommended to change unis or not come back, however you are allowed to resit if you believe you can sort yourself out for 2nd year (the resit marks don't actually count for anything though, you keep your failing mark). So that should give you some idea.
I think if you only just pass this year, then halfway through next year, or in the third year you may have a pass degree scheme.
It really depends on the uni, and the modules. For me I have 11 exams, and I'm sure they won't mind if I get 0% in all the physics modules (although it'd be a bit of a waste...) whereas if I fail a core module then it's unlikely the 2nd year is going to make any sense. Are the exams you think you may fail particularly important modules for your course?