Take a gap year out, get more work experience. If you decide being a vet isn't for you, just enrol next year for your language/linguistics degree. If you really want to be a vet then you have plenty of time in your gap year to get sufficient work experience (at least 6 weeks) to make yourself more competitive to the other applicants. You could easily get around 12 weeks work exp if you arranged it in advance which would severely improve your prospects. You haven't got anything to lose.
Worried about not doing enough sciences? It doesn't really matter, i only did biology and chemistry at IB higher and they took me, similarly i have friends who only did one science and they were accepted. If you're interested just phone up the admissions tutors and ask how they feel about you doing only one science. Again, what can you lose?
Try to sort out your decision as early as possible, i know its not the easiest of things, even at vet school i'm not completely sure i will be vet, i enjoy it sure, its interesting but i just have to wait and see how things pan out. But doing a language and linguistics degree beforehand will make going to vet school extremely expensive. You will almost certainly have to pay full university fees because its your second degree. There are bursaries, etc out there, but it will be significantly more expensive not doing it first time around. I may only pay £3k fees but the graduates pay about £15k per year for the first three years then about £25k a year in the two clinical years. That is all on top of your accomodation, living costs, course materials, etc. I'm an undergrad and i'm looking at £50k of debt, for a post grad that could be in the £100k region. What would be more sensible in my eyes would be to do a vet degree first if you're really interested, then, if you don't like being a vet, go and do a language degree, sure, being a post grad you will pay double fees, but the course costs for a language degree will be much less than a veterinary science/medicine degree.
As you said, a language degree (arts degree) doesn't help you that much when looking for a job (unless you want to be a teacher or translator). With a vet or vet nurse degree its a vocational course with a guaranteed job and profession at the other end, no extra training. I have friends, and friends of friends who have done arts degrees and now, after uni, are working in highstreet shops/supermarkets because their degree doesn't help them get a job, it simply means they join higher up the pay scale (in some jobs). At the end of it, their university degree and student debt has accounted for nothing.