Hi Emma
I'm also from the UK and have just had a fantastic logo created for my new business via
www.designcrowd.com. I can't recommend them enough and have used them several times on various projects.
Basically it's a crowd source website where you decide what kind of design you want (I'd suggest the logo and business card combined option) and then you fill in a brief which also includes setting a budget for how much you're prepared to pay. At the time you submit your brief you make the payment which sits with Design Crowd. Your project is then launched and promoted out to thousands of designers all over the world who will then submit designs to your project. I personally had around 100 different designs submitted to me over 5 days from people from literally every continent. During that time I managed to whittle down my favourites and get them to create countless adjustments until I was happy. I then decided which one I finally liked and declared them as the 'winner'. The winning designer then sent me the logo and business card design in all the relevant formats needed for printing etc. I then hit the button with Design Crowd to say I was happy and then they released my funds to the designer. Job done!
One of the great things about this site (aside from getting hundreds of designs to choose from) is the money back guarantee. If you get to the end of the project duration and you still haven't found a design you like then you just get your money back. It happened to me on a project a few years ago to redesign an existing logo and for some reason nothing really worked for me or hit me as better than I'd already got so I got my money back. It was very simple.
I hope that helps. It's a great site and im sure you'll be really impressed.
Good luck.
Janet