I reckon u would be ok with a wash and chami but dont take it for a drive as road grease and dirt would give u problems!
Meths is fine in my experience but you can get weak solvents specially for car paintwork. There is a pre-paint chemical available that is used to de-grease when spraying.
Honestly, as with everything, its the prep work which determines how good the vinyl goes on!
Im sure you'll do it no probs