If you want a vet, you need to know a couple of things before we get started.  
 It's very competitive to get into.  Be prepared for this and consider a back-up plan as well.
You need REALLY good A-Level grades (AAA or AAB) and will need to have studied sciences at A-Level, biology and chemistry being the main two.
There are only 8 institutions to apply for and the degree will be 5-6 years long.  You can only apply for FOUR vet degree courses (rather than 5) through UCAS, so you can use that last place for a back-up plan.
You will need to submit an early application with UCAS, meaning that you need to have you application ready to put in by 15th October so most of your prep needs to be considered in Year 12.
 You will need to have completed work experience for entry to vet school and be able to evidence this on your application.  Look at the institution you are applying for to understand exactly what sort of placement you need.
You need to be able to cope with the squeamish aspects of becoming a veterinary surgeon - blood and guts are the norm!

Items