Perhaps we should compile a list of "economical modes of transport in the UK" for those of us on a tight budget?
The cheapest form of transport has to be walking and for those who want to get from A to B in more haste try running. Then there is the bicycle option, being careful to avoid the many potholes and motorised vehicles.. There is the four legged option such as a horse, camel or elephant, assuming that one has access to such a beast. If none of those options appear attractive then, if one is willing for a little financial outlay, there is the bus.
I am sure that there are more options for the thrifty traveller in the UK that I have missed, please add.