Nowadays there are many websites that help you track what houses have sold for which ultimately take information from the Land Registry so that you can see the true dates and figures.
www.rightmove.co.uk and www.propertyfinder.com are currently the main independent websites that most estate agents advertise on. Therefore if you place your postcode and a brief description into the relevant section, you will be able to see what the house prices are. Ultimateley you can always get three estate agents to come out and value your house for you as well.