There was a statistic on erowid regarding meth and cocaine, unfortunately i can't find it atm. Anyway, it claimed the addiction rate amongst cocaine users is 70% (meaning approx. 70% of users are addicts) while the addiction rate amongst methamphetamine was said to be 90%.
As has been said, it can be found around the UK in the bigger cities, but hasn't made much of an impact across the country yet. With pills and now cocaine getting stupidly cheap i guess some of the market for it dissapeared.