You see an off plan, you pay say €5000 as resrvation and sign a contract say 28 days later.
You have a choice
1) Take up builders mortgage ( subrogate) in which case you have to wait until the property is completed, say two years ( if you are lucky)
2) Get a non builder mortgage, No lender will commit to a mortgage where the draw down will be in two years time. ( I can see why) in the mean time perhaps you have paid 40%