Yep - all vet med applications have to be in by the 15th Oct. (It oxbridge, med, vet med and dentistry for that deadline). You may well have to remind/tell/get irate with teachers and schools who don't seem to realise about the deadline. Plenty of people find it getting nearer and nearer and still have no reference done etc. At the end of the day, its your application, for your future career, so make sure you are pro-active getting it in in time!
The other date to bear in mind is the BMAT. Don't know off the top of me head, have a look at their website. But there is a deadline for booking to sit that (normally sat in november I think). If you are applying for RVC or Cambridge you will need to sit this, again, don't rely on your school thinking about it. Make sure they sort out and enter you for it.
Work experience wise, try and get as much done as possible before you apply (have done sounds much better than will be doing!) Failing that, make sure you have booked definite things. Sound much better that you have 2 weeks at xx booked, rather than hopefully, I am trying to arrange etc..... If possible try and have completed as much as possible my the christmas time. Some interviews will be before christmas, but quite a lot are after, so it would be useful to have done placements to talk about them at interview. But, they do tend to look at things that are planned and not completed as well I think.