Hi Heidi & welcome to the forum. Try not to worry too much. I know this sounds almost impossible but we have all been there & we all probably thought it wasn't as bad we had anticipated. They are generally nice people and will not accuse or judge you. They will ask you questions relating to the statement you handed in at BR so have a copy with you during your interview. You will probably be asked questions that you cannot remember the answers too so just tell them that. Be honest & open and all will be ok. Your Co-op Cashminder account should be fine. You can tell the OR about it during your interview. And no they shouln't take any wages.
On a different note I would advise editing your surname off your posts, just to keep things more secure. Good Luck & let us know how you get on.