Availability of pure alcohol in the UK (or alternatives as fuel for alcohol-burning cookers)
You can't use methylated spirit to cook that way. Methylated spirit contains 1% pyridine to deter people from drinking it, and it will taint the sausage (and no, they don't say what is in it on the label).

The way that excise tariffs are set up, you could buy pure alcohol in UK, but the duty would drive the price to about £75 per litre.

Better to buy pure alcohol in countries that are used to selling it retail (I always bring back a couple of litres from Italy, about €16 / litre).