At current rates you will have paid €17,000 in interest on your mortgage between now and when you have it paid off.
If you threw the remaining €40,000 off the mortgage you would save €7,000 in interest repayments over the same term with corresponding lower repayments to make.
You have to run the figures yourself but investing that €40,000 wisely over 7 years would in the past have earned you that €17,000 but there is inflation and DIRT to think about.
PM me for with a email address and I'll send you off a handy Excel mortgage calculator so you can play around with the figures for the mortgage or even visit your bank and they will run the figures for you.
IMO when you have a mortgage and you come into some money it is not always the best course of action to pay off the mortgage, as it's the cheapest money you can get. This is especially the case when you can find some other outlet for the lump sum.
You have to decide say in 5, 10 or 15 years what sort of money on deposit would you be comfortable with or need. You are in a relatively strong position with the 20,000 already saved.