In Preston yesterday there was a free cycle ride around the city organised by the Skyride project, jointly run by British Cycling and Sky. With no official start or end time or place you could pop in for as long or as short a time as you wanted and there were lots of activities for both cyclists and walkers around the route. If I hadn't been at work all day I would definitely been there.
To discover how you can get involved in this project, and find some great cycle routes in your area take a look at the website here. Or even just explore on your own somewhere new close to home!