P/UT means Pilot Under Training. Dual is the same thing.
In your training you you should only have need for 3 columns, Dual for dual flights (!!!), PIC for the solo's and PIC under supervision (PICUS) for successful flight tests. I can't say I'm particularily au fait with the Pooleys logbook itself, and they are all slightly different. If there isn't a column for PICUS, then I guess you'll end up putting it in PIC column.