Always use a small tup on first timers. Personally I always use a Shetland tup on my first timers (as do several prominent Texel and Beltex breeders
), whatever their own breed, because the Shetland x lambs come out running, know what they want and where it is, and are persistent in getting it. Exactly what you need with first time ewes
By the time they've reared the Shetland x lambs, they know their job. And my #1 top piece of lambing equipment is a pair of binoculars. I have never, ever had to pull a Shetland or Shetland x lamb. (Of course, now I've said that...
)
I haven't had milk sheep but presumeably, as with dairy cows, you need to give some feed to "feed the bag", while trying to not make the lambs (or calves) so big they have trouble getting born. If so, then Texel would be one of the last breeds of tup I would use, because you are very likely to get overlarge lambs if you feed the ewe.
Does your business model need your sheep to produce good meaty lambs in order to work? If so, then look for something that will give a decent fat lamb without a difficult lambing. If you can grow the lambs on until New Year you could try Cheviot; the lambs tend to be born very small but will make excellent butcher's lambs in the New Year. Otherwise, if you need ones which will fatten in one season, you might do better with a Downs breed, although I have no personal experience of Downs sheep. Personally I have found Charollais tups to be fantastic - easy lambing, very active lambs, grow fantastically well, better than Texels - but others on here have had reported bad lambings with Charollais tups. (I always look for a tup with narrow shoulders, mind, which could be a factor.)
If your business model is more focussed on milk yield than fat lamb or store lamb revenue, then just find a tup that lets your ladies have an easy time lambing whilst letting you feed them up for lots of milk, and don't worry about how "good" the lambs are