Congrats AJ and Mammoth Guy for joining the Rega club! I would love to try the RB3000 but it isn't being sold separately at the moment and the Rega dealer who let me buy the RB880 separately before it was available as a stand alone purchase, hasn't even received a P10 yet, so you beat him to the punch. Now you have no where to go if you want to upgrade your table in the future you're at the pinnacle....maybe cartridge or phono stage?
AJ - I've never been a real tweaker and don't get sucked in by big expensive cable upgrades and other nonsense. Rega designs their tables not to be tinkered with. I guess if you have isolation problems, you should try to remediate them, but the rubber feet were put on the table for a reason. On the P8, you can't replace the power cord from the PSU to the TT as it is hard wired into the table. Same for the tt interconnecting cables. You'd have to completely rewire the whole arm (which Rega just redesigned, so I'd leave it alone). Mats are very important, and Rega put a lot of thought into it - so trust them. I don't know who you are talking to at Rega, but the sales guys at the US distributor don't know much. If you talk to their tech guys who fix them (can't see that happening except for abuse), they will give you the real deal about what you can do to improve the sound (and what won't). They are very nice, and not super serious. They know where Rega cuts corners and aren't hesitant to relay that information. The point of this pursuit is to enjoy the music.
I know sometimes that is tough as we all get obsessed by it at times, but if you read Van den hul's FAQ on their website, it talks about a lot of these things and has plenty of humorous insertions to keep you alert if you choose to read it. They are about the most serious engineers out there and they don't want anyone to lose sleep over an enjoyable avocation. Here is the link:
https://www.vandenhul.com/faq-cables-and-phono/. Happy reading - the hifi tips white paper is interesting, the others can get a bit technical, but still worthwhile. After reading it, you'll never move a cable again.