If me and another pilot shared an hour how would that be logged?
Ooops. Don't start that discussion all over again or Bose-X, DFC and others will just move their slugfest in here...
As a PPL in SEP (single engine - piston) aircraft, you're always flying aircraft for which the authorities think one crewmember is enough. That's the Pilot in Command. Everybody else (unless you're having a flight lesson or exam) is a passenger as far as the regulations are concerned. So if you fly with a buddy PPL, you log the hours (as P1) when you acted as PIC, and he logs P1 when he's acting. As a passenger you could log the flight as "supernumery" (SNY) but this does not in any way count towards any experience requirement for any license issue/revalidation. So it's normally not done unless the flight was particularly memorable and you want to record it somehow for your own memory.
The PIC is the one who makes the decisions, not necessarily the one who handles the controls. You can be PIC either in the left hand or right hand seat but there can only be one PIC at any given moment.
We just had a big debate here a few weeks ago whether the PIC role can change in-flight. Most people think it can, although it is fairly uncommon to do so and might lead to some indirect legal complications. What's more common is that you are the PIC for one leg, from start to landing, and pay for that leg, and your buddy is PIC for the return leg, and pays for that leg. It still comes down to twice the fun for half the money.
If you want to reduce your flying costs after obtaining your PPL, your best bet is to attract passengers who want to share the costs of the flight with you. This is perfectly legal but there are some limitations to it, which you will learn when you do air law. But if you do it properly you can (theoretically) reduce your flying costs with 75% to 25%, by sharing the flight costs with three passengers (weight and balance permitting).