I have 2 current sources:
coffeecompass.co.uk for the quality stuff
and...
TKmaxx for Italian bar coffee. Yes, mad isnt it. I dont know where or how they are getting this stuff but they are, in 1kg bags for about £10. Quality varies from shite to average, and it is the average I'm after. Artisan coffee is great, but I quite like bog standard ristretto per every bar in Italy, and you need a pretty bland central/south american bean and a bit of robusta to get it. Got 7kg the other day in Swindon.