Edd, get something fairly flexible and soft as it'll turn more easily.
The stiffer boots/bindings/boards are more for huge powder days and freeriding which, to be honest you don't get often enough on piste to justify getting.
I'd go for a softish board, middle of the road boots and bindings in terms of stiffness. Most places rated them from 1-10 with 1 being soft and 10 being stiff. Get a 4-6 board/boots/bindings.
Bindings: don't waste your money on the high end ones, as they're usually made from metals etc that are expensive but also really stiffen things up. Any small twitch and you're off in a different direction. The softer cheaper plastic ones are great all the way through intermediate level and are more forgiving. They're also lighter.
Boots: Go for something with a dual lacing system so you can customise the tightness on your foot separately from your calf. Try a few on as different manufacturers are better for different feet. Some cater better for wider feet etc.
One final thing. Unless you're a really good rider and pushing the equipment to the limits, you don't notice much difference in the cheaper stuff to the expensive stuff from brand names companies.