Lots of people seem to get very flustered about P1/us. I feel that it is important to go back to basics:
Are you receiving training for the grant or extension of a license or rating? (i.e. PPL, IMC, IR, CPL etc etc)
If yes then you can log P/ut
If no then it can't be P/ut
P1/us fills in a gap. You can log it if you are undergoing differences training with an instructor or a group or flying club check out. It also applies to successful examination flights and actin commander of a two crew aircraft which the holder has on Part 1 of his or her license - i.e. a rated co-pilot handling the controls. IT MUST BE COUNTERSIGNED BY P1.
There is no limit on the logging of P1/us but I fear that if you flew with another PPL the whole time and logged P1/us to bolster ones' log book the CAA might raise its collective eyebrows.
Hope this helps