Different needles

#1

I have found this pattern at rowan:
http://www.knitrowan.com/editorial-image/pdf/Sheep%20Pattern.pdf
I have the correct wool but not the correct needles, the smallest I have is 4mm not 3 1/4mm am I going to get myself in serious “Do-Do” if I use these?

#2

It may turn out larger. Knit a sample of it with the yarn you have, see if you get the same gauge. If not, you could make a smaller size