Some good info in the answers above – any of the top ski tour operators (inghams, crystal, etc) will do you a “learn to ski” package that’ll include ski equipment hire, ski lessons, lift pass, insurance and half board accommodation. There are some resorts that are more beginner friendly, (eg Alpe D’Huez and Flaine in France, Arinsal-Pal in Andorra, obergurgl in Austria, etc) but most resorts anywhere will have slopes of all grades. In terms of customer service, north America will give you the best learning experience and snow conditions, at the expense of a long journey and jet-lag. Of the traditional ski countries, you’ll probably get more skiing for your euros in austria, whereas switzerland can be frighteningly expensive. Best bet though – go see your high street travel agent for some more advice.
Having lessons beforehand is a good idea – the ski school at the resort will assume you’ve never skied before to start with, but if you have, you’ll get moved up the class fairly quickly. And it’s worth it – if you can – to have at least some of your lessons at one of the real snow slopes in this country; these are at Hemel Hempstead, Milton Keynes, Castleford, Manchester and Tamworth. “dry slope” is a bit of a misnomer; they hose them to make the surface run better, which means (until you learn not to fall over) that you get very very wet.
4 is a great age to learn to ski – a kiddie’s centre of gravity is so low that they soon learn to stay upright in virtually any conditions and they whizz past the grown up beginners in no time…..