Year 12 Veterinary work experienceWatch
But basically how far can you travel? If you have pets your own vets are a good place to start, if not google vet practice and go on maps and find all your local practices. The best way hands down in a normal world is to visit them in person and ask about the possibility of a placement - this will be most unwelcome now. An email followed up by a phonecall if no response is probably your way to go here.
Explain your request to see practice with them to gain experience prior to university, why it is you want to be a vet, why you want to see placement with them (sure something complimentary can be made up here), the dates you are looking to see placement - and maybe something showing you are aware of COVID restrictions and would take all precautions if a placement was allowed.
I would personally recommend putting your grades on also - to be harsh a vet practice is less likely to waste their time with someone who has no realistic chance of getting into vet school - especially with the COVID risk of having an unnecessary person in practice.