Hi you knowledgable people. I've just bought a set of 4 18" alloys off a L322 and intend fitting 'em to my P38A. I've also bought spigot rings from Emmotts, but as i was reading an E-bay ad. (need to buy a spare) it suggested i will need the nuts from a L322 as well. What size of nuts and is there much difference?

Measure the bolt hole from the back of wheel.
either 20mm or 23mm you need that size nuts to suit, if I remember correctly..