Thanks for the help folks!
ive fitted a brand new kmc x1 chain which is intended for single speed use (originally on the bike) but i have removed another link to pull the tensioner a little tighter. (pictured)

no luck though, it still skips under torque :S

The jockey wheels of the tensioner however are tight up against the left side of their cage (see pics) but its at its furthest adjustment in the direction it needs to go. could the lack of float in the pulleys be steering the chain off causing skip ?

The more i look at it i think this may be an issue, not sure.
the only way to move the arrangement the 1-2mm over to the left as though looking at the bike as in the picture would be to remove meat off the tensioner or the derailleur hanger.
but before i go chopping i was just going to try a cheapo eaby tensioner adjusted with the chain line better first!?
what do you guys think!?

thanks for helping me out so far!
regards Tom