We only feed haylage here as we can get small bale haylage that's cheap and easy and more available than small bale hay.
We have fed some very poor hay before and the hebs loved it.
I would expect them to do just fine on hay or haylage, whichever suits you best. Keep an eye on their condition as you get to around Feb/March if you're looking at sending away April/May and you could top up if they're lean, or just give them a wee while after the grass comes through to put on condition. Ours are usually fat after the summer, with only lick buckets and a handful of coarse mix (must be "suitable for tups" when feeding boys) fed to the whole field (ewes with last year's hoggs) before and up to the end of lambing, and only top up of hay/haylage through winter.