I think the first thing, before calling to Revenue, is to work out approximate figures.
Were you in 2008 given your full Paye allowance and your wife's personal allowance, for a start? Check you have been claiming all your tax credits for the years since.
You can download Form 11 and off-line software from the Revenue site, and work through offline to give yourself some idea of what, if any, underpayment there is. If you have been paying UK tax on your wife's deposit income I cannot see there being much of a liability. You can set the UK dirt against Irish liability.
The Form 12 does not have to be submitted for months yet, so no panic.