Goats milk is slightly lower in fat content than sheepskin milk. However, it is a very good substitute, and personally I would rather use it than buying in powdered milk.
Goatwriter, I'd also be interested in where you get your lamblac from, prices round here are a minimum of £30 for a 10 kg sack!
We have reared orphan lambs on goats milk for over 30 years, and had more issues when we have had to use powdered milk.
Freethyme, sorry but I am bit far away, and don't know that many Goatkeepers in your area.
Beth