Price range is £4-500, as for memory, what's best? I read that HD can be shakey and it's best to use a tripod? So different to using a dv camcorder, is this correct ?
The only inherently shaky cameras are the little Flip-style ones. They don't have image stabilization, and their small size and light weight make them harder to hold perfectly still. With a consumer camcorder you can use your right hand to grip it and your left to hold the lcd screen, making it more stable.
As other posters have mentioned, you need to decide if you want to record to flash, hard disk, or tape. HD tape camcorders are harder to find, and the only consumer ones I know of are the Canon HV30 and HV40. Both are considered great cameras. Other manufacturers might make tape-based models, but I'm not familiar with them.
Flash and hard disk cameras are easier to find. I'm only familiar with Canons, but there are other brands obviously. Flash-based cameras tend to be a bit smaller and lighter than hard disk ones. The downside is that they use SDHC cards, which can add up (although they are getting a lot cheaper). Hard disk-based cameras tend to be a bit cheaper than flash-based ones, but they are a bit bulkier and you have to be careful about knocking them around. On the plus side, with a 60 or 120 gig drive always attached, you'll always have plenty of space for recording. Also, most of them (well, the Canons at least) will allow you to record to SDHC or offload already recorded clips to SDHC, meaning you have limitless expansion.
The big downside to all non-tape consumer HD camcorders is the time it takes to import your clips. You'll have to convert your clips either to AIC (iMovie) or ProRes (Final Cut) in order to edit. This can be as fast or even faster than importing tape, but it depends on how fast your computer is. With older computers, the transcoding can take a while. Also, tape is easier to archive.