If you have extenuating circumstances, I believe you can ask the exam board to take this into account? Please let your tutor or someone know so they can get the ball rolling on this as it's a bit late.
If you don't get the exam board to take extenuating circumstances into account, then sometimes the vet schools will, but you will still need decent grades - you need to contact them to find out what their policy is with this.
If neither of these above options work out to get you into vet school then your next choices are:
Take a year out and resit - if you can get over the mental barrier of feeling 'left behind' when your friends go off to uni, this is by far the best option. Many people you know will end up taking a gap year anyway, so try not to feel like this is the 'bad' option - it'll give you the chance to become even more prepared for vet med, and you'll still be roughly the same age as most other students when you arrive at uni.
Or, go through clearing and try to enter the graduate vet med route after completing your first degree in biology/zoology/other. This is not only time consuming, but very expensive. Additionally, graduate vet med is more competitive than undergraduate, so you may find it much harder to get a place and there is no guarantee that after all this work you will even get in. You are also unable to get a loan for your vet med course after the first degree - you would need to fork out £9k per year at least for your tuition fees. Also, it's worth noting that if you are really passionate about veterinary medicine, you would have to spend 3 years studying biology or something - this is not where your passions lie, and you may struggle to remain interested in the course you choose for 3 years.
I think your first step should be to contact someone from school/college to see how you can get your extenuating circumstances taken into account.
I hope this helps. Good luck.