I have fitted a few coffee roasting machines and the beans come in sacks, if you try your local tea/coffee merchant they will usually be lad to be rid of them.
I did a quick search on google -
Whittard of Chelsea, unit 59 High St, Leicester, LE1 4FP
0116-251 2679
If you still cant get any locally i friend owns a tea merchants and i could get some from him but if you want to collect
russ