Right work experience?

Anything with animals will count, but make sure to cover the basics before doing fancier stuff.

Generally universities don't really count 'volunteering' that you have to pay for since those opportunities aren't available to everyone.

For work experience there are obviously things you should do ( lambing , cattle , large animal vet ,small animal vet ect.) but is there anything you shouldn't do or won't count I don't want to waste my time doing the wrong thing??? ( was thinking of taking a pre-vet course / volunteering in South Africa) ?????

Little Tail Chaser has pretty much summed of most of what I would say.

Just a few points I'd like to add:

The view I heard from an Admissions tutor at Liverpool is that they view volunteering in places like Africa as more of a holiday than anything relevant to the degree (which focuses more on UK domestic and production species). At Liverpool you will be send a questionnaire and will only be able to count 1 week for such 'exotic' placements, and will be limited to 6 weeks for each husbandry placements and 4 weeks at each vet practice.

RVC places restrictions on placements in that they have to be within 18 months of applying.

Having said that, placements that won't count for one uni may well count for another so it depends on where you want to apply!