Varible speed isn't so important if you're not turning large stuff, where it comes into use is when turning out of balance pieces. Sometimes a blank will shake like hell at e.g. 300rpm but be reasonably steady at 350pm. A couple of cuts later it might start to shake again and be perfectly OK at 380rpm or 320rpm - there's no real logic, sometimes a few rpm can make a difference. Many people manage perfectly well for decades with fixed speeds but no one who has variable speed would happily go back to fixed speeds. Don't forget also that you can turn very small things on a very large lathe but not the reverse.
( I assume the club is at Wheal Jane - Cornwall Woodturners? I'm not far from you - Carharrack.)
