I would say try Enterprise car rental. They have competitive rates and they will come and pick you up, take you to their rental outlet to get your car, do the paperwork and you're on you way...

As well as pricing hiring over there, you should try pricing with http://www.carhire3000.com and http://www.netflights.co.uk On the forums I visit, people from the UK recommend them as they have good rates and you can pay all your insurance up front including a platinum package which includes a full tank of fuel and an extra driver.

luci

Thanks folks! I'm now well on the way to getting sorted.