Most unlikely as part P is BLDG REGS, as are parts L..energy efficiency, M disabled access to switches etc. so nothing to do with IEE regs.
you need part p if you intend doing domestic work, there is nothing new to learn if you already comply with regs.
don't know what all the fuss abt. all you need is a job or 2 to show inspector from whichever scheme operator you choose to go with, plus test sheets for those jobs, prove you can use your test gear, show all regs books guidence notes 1,3,7, answer a range of questions on site and their registration fee. You then get a pass word and member ship number to allow you to log on and register each job, pretty stickers for your van, pay a small reg. fee for each job, and keep everything 100% right because your annual inspection seem due very quickly!
good luck, SPARX