UK spark plug cross reference information can be found on the instructions when purchasing a cross spark plug that works in the UK, or on websites that provide information on cross spark plugs.
Champion Spark Plug QC12YC
Most all brand spark plug brands are on the cross reference including Champion. Some of the brands that cross reference to Champion are Autolite and Denso,
Many spark plugs can be interchangeable if they fit the motor in question. To find out which can cross reference with the Laser 40500, a cross reference catalog should be referenced.
Champion RJ19LM
Champion rj19lm
Champion N12YC
SP-34 is the number of an aftermarket spark plug available from Arnold. It should cross-reference to a Champion RJ 19LM.
Bpr6es
Ngk bpr5es
you can just use a j4c without a resistor
RC12YC in Champion