where is all this money coming from to plug the £15bn gap per annum?
with all due respect Ireland is not as prosperous as you make out. Yes it has billions added to its GDP by virtue Amazon, Facebook and Google's EAME operations are based there, but that does not translate to wealth within Ireland. The aforementioned companies pay less than 1% corporation tax in Ireland, hardly contributing to taxes.
Can we see this report? As it stands, the deficit of £15bn is around 20% of GDP, now bear in mind, during the Greek sovereign Debt Crisis, government borrowing peaked at 10% of GDP. You appear to be advocating starting in a situation between 1.5-2x as bad as the Greeks found themselves in ten years ago.