Skygirls thanks. Will check Polarn O. Pyret and Bush Baby out. Never even thought of Snow and Rock and outdoor shops - just assumed that they'd sell stuff for kids of ski-ing age, but will have a look.
Also look at Jojo mambabe Polarteric all in ones. Try to use lots of layers. Dont spend a forturne as it wan't fir them next year! Take two pairs of mittens so you have a pair to use while one set is drying