Your school's situation will have already been accounted for in your offer, but dependent on the university they may be prepared to be more lenient. No-one can tell you any more, really - whether a university is strict is dependent on the admissions department, who themselves don't even know on the day (if more people than expected have firmed and met their offer, they will be stricter; if fewer people firmed their offer, or many have missed it, they'll be much more willing to accept students who have missed their offer).