We are amongst those who don't vaccinate, but then we rarely buy in new stock, and we review our decision each year.
Ask about worming, but we would worm with the best possible wormer before we let the sheep out of the trailer, and leave them in overnight to shed any worms, then burn the straw, whether the seller has done them earlier or not (unless they have just wormed that day). We don't want to bring worms onto our clean ground. Same with fluke, but ask your vet's advice on what to use for your area and the time of year. Vet will also advise on flukicide regime as you are on wet ground (fluke uses a water snail as a host).
Once the sheep are yours, as you will be starting with clean sheep, they should only need worming after a FEC (faecal egg count), done by your vet, if they are looking a bit peaky, stark, skinny or wet daggy