Its ok Danndans.....I love Dexters really......
Re apple trees.......some sheep will totally ignore them......some will behave like unattended children in a chocolate shop!!!!! Personally I would construct hefty tree guards, triangular with 3 posts and stock wire well out of reach of the sheep...........and if they really want to destroy your tree its surprising how far a small shep can reach
I would go for getting some ewes with lambs .........if thats your initial choice, from a reliable source such as a good local farmer with a reputation he wishes to keep intact!!!.............or take a very experienced person to market with you...........I have got some good bargains in market.........urrr and also some 6ft fence jumpers
you take a chance there!
As for pedigree breeds........
Easy lambing breeds are to be recommended ..............but do not forget your second valuable crop....the wool!! eg Ryelands, Dorset Downs, Gotlands, Shetlands (but make sure they are not wild!!!) Ouessants (lovely wool, good carcase for a small family wanting just to eat their own) etc