I've no issues with a Lleyn tup for your girls, but a Charollais would be equally easy lambing, very active lambs, and would grow into better fat lambs. So if you had problems finding a Lleyn, a Charollais would be fine.
Texels are quite different. The lambs are bigger and chunkier at birth, the skins (fleeces) are rougher, so more friction in the birth canal, and the lambs are much more likely to be dozy and not get up and find the milk bar - or continue to chase an inexperienced ewe if she's running away from them.