- don't feed cake to groups which are lambing; the disturbance can result in ewes leaving newborns and not getting back to them in time - this is a bigger problem with twins and triplets than with singles (but you probably aren't caking the singles anyway)
I dont think this is such an issue with small flocks, and I would avoid any change in feeding patterns. With my BWM new mothers won't even come to the feed trough for the first few days, they prefer to stay with their new babies, to the point where I have to go and take them their own personal feed trug whilst the others are eating!
I think the watchword is "be prepared" and assume that the weather will be rubbish. Keep an eye on the forecast daily. Even if you don't have any indoor areas you can knock up some make shift shelters easily and cheaply with pallets, hurdles, tarps, straw bales, spare pig arks, old gates, old doors, etc etc. Make sure you choose a lambing field that has as much natural shelter as possible from hedgerows, trees and wot not. Have plastic macs on stand-by.
Be super clean in everything you do, copious use of stuff like Stalosan. Dunk your wellies in a disinfectant bucket often. Avoid stressing the sheep. And make regular checks on all animals, without fail - I would do every 4 hours, but I don't tend to do overnight, but would do if the weather was extreme. Have plenty of pairs of waterproofs handy for yourself so you can put on a dry set whilst a wet set are drying off.
I lamb outside but bring new borns inside for 24 hours or until I am happy that they are fit and well, then they are turned back outside.