I am looking at buying a new cordless drill
I guess it all depends on what you're using it for and how often. I bought a DeWalt 14volt hammer drill since at the time DW only sold a 12 or 14volt right angle drill (and this is one useful piece of kit for working in floorspaces !) They now sell an 18 volt one, so must be even better.
I'd recommend the Bosch 'green' range for light/DIY use or the Bosch Blue or DeWalt for trade use. The DW 14volt hammerdrill gets used for most drilling, screwdriving, but I've also got a corded SDS for drilling holes larger than Rawlplug sizes.
I'd get batteries of at least 1.7Ah if you're doing much more than putting up a shelf kinda work. Get at least two batteries and make sure they charge in an hour or less. Finally, (sorry Screwfix) I've found www.diytools.com (aka Powertek) to be very well priced and CSMabrasives (www.sanding.net) to be the most helpful power tool suppliers. Oh yeah, don't buy anything by Ferm, unless you intend to throw it away before too long - really are Christmas Cracker quality I'm afraid (had a sander that just sort of self-destructed after a couple of hours use).