If you are talking good heavy (20-25kgs) small bales of hay, one bale will feed 30-40 commercial sheep on grass for one day. Hebs will eat less, of course - maybe 2/3 as much as a Texel or similar.
If they have no access to grass, they may eat up to twice as much hay.
So in theory, if you are keeping the tup for 5 weeks, and there's effectively no grass, 9 -10 bales should be more than plenty. Put out a flap or two night and morning, spread out well. If they clean it all up, give them a little more next time. If they leave any / sleep on it, give them a little less next time.
If your bales are small and/or lightweight, then of course you will need more of them
They'll need plenty of fresh water if they're eating hay.
If it's a tup lamb and he's coming off grass, I would certainly put out a feed block too. You don't want the girls' nutritional levels to plummet, either