OK. I can't tell you whether your existing house after renovation is better than buying a new house. That is a decision you have to make for yourself. But if you love your house, then staying with it seems like the right idea. You can buy a house somewhere else and then find you don't like it. Good location and good neighbours are worth more than the right kitchen worktops.
Releasing equity is not a good idea. Either sell it and use the proceeds. Or alternatively, can you finance the upgrade without selling the apartment? Then you can live in the apartment while the upgrade is going on. €150k means that you will be out of the house for 6 months.
Maybe the Credit Union would give you the money if your bank won't lend you any more.
If you do stay in your house, then I doubt that upgrading it would be that urgent.
Brendan