My previous chainrings were 52, 40t. The derailleur is laterally too far from the chainrings. The UN52 does have a slightly shorter spindle by the look of it so I'm going to have my lbs fit it tomorrow (hopefully)...too many different tools to bother myself! Hopefully that will bring the chainrings within the fds reaching distance perhaps with some lower limit adjustment on the fd.
I'll post again tomorrow if I get the bb replaced as I'm sure I'll have run into another problem!