Yes it’s a good idea to provide some shelter - but hedgerows or walls, a biggish clump of rushes, a few overhanging trees, are all good shelter for sheep. The ewes still have their fleeces, and the lambs have their mummies! If you just have bare fences, you can make shelters with the oblong straw or hay bales, or with an arc of corrugated tin (like a pig arc but with no bottom or ends, move it around frequently), or even with panels of tin strapped to the fences. Great shelter for lambs are old tyres, they get inside and curl up snug as anything, and you can move the tyres around unless they’re enormous.
If you want to use the stables, I’d say they’ll need three stables with that number, if you have them. Each ewe will try to keep a space between her family and the next, so ten families between two stables is still rather crowded. How much space depends on the ewes and the breed - hill sheep need a lot more space between them than something like a Downs breed. If the stables are 12’ square, three would just about do for ten families. If you don’t have enough stables, watch out for anyone getting bullied and maybe provide other shelter - straw bales or whatever - nearby.