Whereabouts in Normandy?
Why do you want to purchase Leaseback? What attracted you to the scheme? Is it the guarantee element?
Have you thought about what happens after the guarantee period end?
Have you looked at similar properties- ie one bed apartments in the area which are for sale through estate agencies, both new and secondhand and checked the rental market? Even googling Agences Immobilier Normandie will get you some results, but even beter if you put in the town/city.
Have you checked both the French and Irish tax situation both with regard to income tax and capital gain tax on a sale.