I've just remembered that the Natural Fibre Co now has a felting machine which can turn out insulation batts - could be worth enquiring about cost, or just chatting to them about how they prevent infestation. If you just use raw fleece for insulation it would definitely get colonised and I don't know how best to treat it to prevent that. Even if you just washed the fleeces in rainwater then layed them out to dry that would help a bit by getting rid of the smell which attracts insects. Some of the commercial stuff is made like a sandwich between two layers of foil.
The people you are buying from should be able to give you information about fleece qualities, and the Shetland Sheep Society website will have more information. Even though you won't have time to spin the fleeces yourselves, it is a good idea to understand what makes a good or bad spinners fleece so you know what quality your fleeces are.
Your new lambs will be SOOO cute
