The Grand Massif area (Flaine, Les Carroz, Morillon, Samoens, Sixt), is only 45 or so from Geneva and Flaine is high, though ugly, so nicer to stay in one of the traditional villages. It's very child-friendly and looks pretty good for beginners.
Les Gets/Morzine are also only about an hour from Geneva, although they're lower and it was quite slushy at the base when we were there the third week in March last year. Nice towns though, good eating, lots of gentle groomers to progress to for beginners.
Thanks for your replies. I'll look into all suggestions, although our circumstances have changed somewhat now as DH is skiing at the moment and called to say he has pulled a ligament and is coming home early. If he is ok to ski again we can book last minute.
Also would like to be close to piste etc and not too long a transfer time.....
You could go somewhere like Val Thorens, but I have been skiing the first week in April several times in resorts c1800m, and had a good time. The snow can be a bit slushy, and there may be patches in the snow, but that can happen anywhere.
You have picked a good year - the base is a lot better than last year. How late can you leave booking?
FWIW we are off to Austria with some friends that week. I am not expecting the snow to be fantastic (as it was at New Year), but I am hoping for some nice sunny warm weather!! And that is important for beginners, especially children.