I'm copying and pasting this in from my posting in another thread about the same topic, as you should bear this in mind:
When I was discussing e-drums around town, my local music store sales guy said, "Whatever you do, don't get an Alesis. If you do, it will be back here within a matter of weeks because of some malfunction, and Alesis will be extremely unhelpful when I call them." Problem was, I had already bought a DM8 USB. And, the rubber came right off two of the toms, then the kick drum quit altogether. Another dealer, the one where I bought it, kindly shipped me another tom (it broke too) and said that when he contacted Alesis about my dud kit, the response "wasn't pretty!" Long story short, I returned it for a full refund and got a Roland TD-11KS for $900 Cdn,, added a fourth tom and have never looked back. OK. it's an entry level kit, rubber toms with single triggers et al,, but it suits me very well, and i feel I can hit it all i want (the Alesis sounds are great, IMO, and varied, but the build quality is lacking). Haven't tried Yamaha, but the choice really is only Roland or Yammie!
Here's a good deal for you in the UK, although over your budget (but has some free stuff!):