Sounds like bringing them inside is the way to go , this will as said allow the grass recovery ready for lambing and yes it would be ideal to split the paddock up ,even with electric fencing this might allow you to make hay on an acre or two next summer . The barn needs to allow plenty of wind above sheep level the temp inside the barn should be the same or cooler then outside , inside they will use large amounts of straw / sawdust / woodchips to keep clean and dry . Since you are already feeding concs and are only 9-10 wks pre lambing don't stop or you may create more problems ( have a look at flat rate feeding ) . have you scanned ?? Don't be in too big a rush to give hep p , you are boosting immune levels for the colostrum , if all your sheep lamb in 1wk then end of jan ok but since they probably wont then some time in the first half of feb will cover all