Thanks for your replies. We had a fab time - ski-ed in Argentiere (Chamonix) on the first afternoon before heading over to Italy.
We then ski-ed in Pila, Courmayeur and La Thuile while we were away.
Pila was our favourite - quiet even during half-term week - Courmayeur was extremely busy and La Thuile very cold - I would only recommend going to La Thuile if the weather isn't freezing cold and windy.