Personally, I think I would opt for Ulster Bank's "Loyalty Plus" variable rate product (currently 3% at your LTV) in your circumstances. That comes with a fixed cash back incentive of €1,500.
If you do want to fix (and I think there are good arguments for fixing at this point in the rate cycle), then you might want to also consider BOI's product range.
As an aside, €600k is obviously a very large mortgage and you will be very exposed to any interest rate increases in the future.