Off the top of my head, rough prices:
Dealer Independant
P1 £200+ £120 ish
P2 £300+ £200+
P3 £380ish £300+
Prices based on the owner not supplying their own oil.
Obviously, those are VERY rough figures, and in no way gospel.
Interval is 9000 miles/12 months and goes P1, P2, P1, P3, P1, P2, P1, P3 etc etc