Running

Running is the best cardiovascular exercise there is, and putting on a pair of trainers and going for a run is certainly a lot cheaper than joining a gym. It can be a bit difficult to motivate yourself when you first start though, so it might be worth joining a local running club. Some of them are very beginner friendly. Here's a list of running clubs in the UK:

http://www.bedfordharriers.co.uk/Home%20Page/links_to_local_running_clubs.htm

If you're in the relevant 50% of the population, you could also have a look at Women's Running Network, which was founded in 1998 to inspire women of all ages to run for fun and fitness:

http://www.womensrunningnetwork.co.uk/

As far as trainers go, New Balance last for ages and are (amazingly) manufactured in the UK.

Football

Instead of forking out fifty or sixty pounds to go and see a bunch of spoilt millionaire kids from wherever over-act, why not go and see your local team. It can be just as entertaining and a fraction of the price.

Here's the Isthmian league's website:

http://www.fansfocus.com/forums/ubbthreads.php/ubb/postlist/Board/2/page/1