I beleive clinic ace is a good one, they sell it in the DIY store near me (Wigan) it's about 60 quid, but huge coverage with it. I saw it being used by some groundsmen once and it killed everything inlcuding very waxy leafed plants like ivy. although someone told me to mox some fairy liquid in with a weedkiller to break the wax down and penetrate leave. Think that may even have been said on here? Heard it somewhere