If you're late it is a 2000B fine. Don't go just to pay this fine, pay it when you next need to go to Immigration for an extension or something. If 8 days late or 8 months late the fine will still be 2000B and no other consequences.
If you don't have a Thai bank account then getting the Non-O from outside Thailand is the only option and can mean a stay of two weeks or more in the country where you are applying from. The Embassy website will have their specific requirements for the Non-O application but a bank statement of one to three months is sufficient.