The ideal for any sheep over winter is :
- available shelter
- freedom to exercise and graze
- hay or silage (or haylage) when the grass is unavailable or has lost its feed value (after Christmas up here)
- access to unfrozen water
If they're not in lamb and aren't lambs themselves they shouldn't need any hard food.
If it was possible to let them wander between grass and the stables at will, that would be ideal for them. Otherwise I would teach them about the stables (have them in a few times, give them some hay there) - if the conditions become such that they'd rather be in, they'll stand at the gate asking to be in and will walk in when you open the gate for them!
Lucky sheep

If you do have them in, keep the ground under their feet as clean and dry as you can - with only two you shouldn't get too many problems, but walking about in each other's poo and pee can lead to foot problems when sheep are kept indoors for any length of time.
Oh, and if you haven't overwintered sheep before, do you know about giving them fluke meds, minerals, vaccinations? If not, shout and we'll inundate you with advice!
