It depends what the caution was for and how long ago you were given it. By accepting a polioce caution you are admitting you were guilty of the offence - never accept one unless you really are guilty.
Drop me a pm if you like with some details and I can give you some advice.
You'll need to be a full member of a home office approved club before you apply for the FAC and the acquire and keep.
regards
Saggs