rockwool is for rooting plants, get yourself some 20 gal pots or even them ice buckets they sell at wal mart work they bout the same size and tend to be cheaper, last year i did 15 gal pots and did surprisingly well.
Walmart acquired ASDA in the UK in 1999.. Since then, it has grown into europe's largest retailer.... Walmart is everywhere.... maybe on the moon one day too....
LOL, no worries, I just thought it was interesting... I learned a long time ago to never say never when Google is fingertips away. I saw your post and thought, if they have them in China, why not the UK?
Sounds like 10 to 15 gallon ( 38 to 56 liters ) with good soil mix should do the trick, although you may have to tie them over at the end if all works out mate. Here in Cali it's pretty easy to get a 2 meter plant out of a 10 to 15 gallon pot.