I took a 30mg prescribed oxycodone at 8am and need to drive at midnight, is this fine if i feel normal, or would the side effects still be there?

That is a large dose: and should only be given to people who are used to talking that large a dose (who have been on lower doses that are no longer working). While in most people the dose would be long gone, if you have been taking them regularly, and particularly if they are the long-acting form, they may still be having activity. Talk to your prescriber and/or pharmacist who know your history and conditions.