ok took advice on here - and reduced arm curls -and tried putting other exercises - utilising more whole body instead - did allow me to do more (and more variety) bench press - and I did feel more tired this afternoon so thats got to be good 
I mixed benchpress (flat) "machine" - the ones you have to rotate the bar into
and "free" - barbell ones - they were as I expected ... hard work - only managed 18kg on each side - but I could feel all of my middle of myarms "quivering" so thats a good sign additional smaller muscles also getting exercised
question though - whats best method to dismount ? ie your doing the benchpress with a barbell in each arm - you finihs - do you try and sit-up (managed that first couple of times but then not) - or lower as far as you can down and then drop them to the floor?
finished the day off with an 8k run in the rain tonight
was really refreshing
cheers

I mixed benchpress (flat) "machine" - the ones you have to rotate the bar into
and "free" - barbell ones - they were as I expected ... hard work - only managed 18kg on each side - but I could feel all of my middle of myarms "quivering" so thats a good sign additional smaller muscles also getting exercised
question though - whats best method to dismount ? ie your doing the benchpress with a barbell in each arm - you finihs - do you try and sit-up (managed that first couple of times but then not) - or lower as far as you can down and then drop them to the floor?
finished the day off with an 8k run in the rain tonight

cheers