1) It makes no sense to borrow at 5.5% interest when you have money on deposit earning you nothing, so if you do buy, buy with cash.
2) If you do buy, make sure to buy before the 31 December as any Capital Gain will be free of CGT if you hold it for 7 years.
3) Given the sporadic nature of your income, I think it's unwise to invest in property. If you need to access your savings, you won't be able to do so without selling the property.
You have a very valuable tracker. There is a small possibility that the lender might offer an incentive to pay it off early. If this arises, it's better to have access to cash.
You have a valuable tracker. If your income drops, you need to be in a position to maintain the repayments , to make absolutely sure that you don't lose the tracker.
4) For a number of reasons, I think you are better off buying a portfolio of shares
Over the longer term, the return should be higher
It's far more flexible, you can sell some of them if you need cash
It's a lot less work
It's better diversification for you as you already have a stake of €450k in the property market