kate, I can't think of any pet lambs I've lost through weaning. Just make sure they are at least 5 weeks old - up to 8 or 9 weeks is fine, just costs you more milk; get them eating creep (as you are doing), gradually decrease the milk (I cut out one bottle feed then another down to one at bedtime) while increasing the creep up to half-a-pound per lamb per day (and try to be sure both are eating it, not mainly one eating it and the other just mouthing on at it.) Then stop the milk and increase the creep with appetite up to a pound per lamb per day. Keep them on limited grass - enough to nibble on at, but not so much long lush grass they can blow themselves up with it - with ad lib fresh hay and fresh water at all times. Keep an eye on their condition - if they seem to be going backwards (you can start to feel their ribs, for instance), maybe put one bottle back in, but not a large feed, until they regain the lost flesh. Give them a week or so and try again.
Once they've been off milk for a few weeks, you can let them have more access to grass.
Don't forget their vaccinations, worm if you get dirty bums, keep reading and talking to us on here (you'll see people start talking about flystrike treatments, for instance, so that'll key you into when you might need to do yours), and you should be fine.
