As above, unis don't see your mocks, they only see your predicted grades which are set by your subject teachers, so I'd speak to them about what they want to do for those - maybe they'll let you sit some papers in September for example? Work experience may be an issue, however you still have time to try find some this summer - currently most of the unis still have relaxed requirements for this so it is something to look into. There's no issue in taking a gap year to apply though and get well yourself and work on your application, having grades means you get unconditional offers which takes the pressure off a bit, and a lot of people on the vet course aren't straight from A Levels anyway. I applied in school the first time and got all rejections so I reapplied on a gap year and just finished first year at Liverpool. You could see if you can apply in Year 13 though purely as there is still a chance of getting in, and you'd at least be able to experience the application process which I think is very useful overall.