I know the xt rims are ust compatable but can you just run ordinary tyres with
sealant in them or do you need a rim strip?

No rim strip needed – spoke bed is completely sealed.

Ordinary tyres will work but some are easier to mount and inflate than others. UST or TR tyres will work best (I've always used Bonty TR tyres which are easy and seat really well but I've tried ordinary Conti tyres which didn't sit very well on the bead hook)