Water will work, the alcohol improves charge cooling some as it evaporates quicker in the intake tract, provides a bit of energy as a fuel, and prevents freezing.
If you have no issue with freezing you should get by just fine on straight water. Some of the Buick Grand National folks here in the U.S. use drug store rubbing alcohol either straight or mixed with water.
As long as you stick with mixtures that are compatible with your pump, and such you can use most any alcohol.
Not sure about in the UK, but here in the U.S. one of the cheapest sources is a dealer that supplies race gas. If you have any race series over there that runs alcohol fuels, try talking to the guys that run in that series, they will know where to find it.
I did a quick search on drag racing in the UK and methanol and found these links that might give you a starting point.
http://www.turnerracing.com/
http://www.automotive-links.com/mot/dra/drg.htm
Methanol is also used by electronics manufactures to clean soldering resin off PC boards ( or at least they used to) so you might also touch base with any electronics supply outlet and see if they sell it.
Larry