They are better with fresh air, but dry + no draughts, plenty of hay for their 'central heating'. They should grow nice thick coats.
I also have Toggs, (+ a BSx).
Over the back half of their pens I put boards over, makes a cosier area for them to sleep under (4' high), also makes a handy shelf for extra hay bales for insulation. Last year I ended up just leaving all the hay they pulled out onto the floor and throwing the dry onto their beds at the back, just keeping the front round the pen doors clear, heavy work cleaning out in spring though!
feeding sugar beet soaked and still warm would be welcomed, and warm water.
I made a couple of waterproof coats just to keep their backs dry and warmer if it was a cold wind but have hardly used them. (I like them to get out and have some excerise if the weather is decent).
Of course like humans different goats may feel the cold more? I just try and remember they come from Switzerland, must get fairly cold there!