Selling a house, new one being built

I am about to sign a contract for a new house in a development that will be complete in about 10 months. Being in Cork, I face the joys of stage payments and face the problem that I will need to pay for most of the new house before selling my current residence. I owe approximately €20,000 on my current mortgage currently.

Taking into account the proceeds from my current residences sale (in or around 400,000) I will need a mortgage of €250,000 on the new property, but of course the problem is that I will need to pay the builder substantially more than that over the coming months, before selling my current residence.

I'm not sure what my options are, but from reading other postings on this site, there appear to be a couple:

1) Get a larger mortgage on the new property and use the proceeds from
my house sale to pay off the "extra" part of the mortgage in 9-10
months time.

2) Get a bridging loan, if this is possible.

Any comments on these sguggestions or other ideas would be most appreciated.

If you ask for a interest only mortgage on the new house, so you only pay interest on what you draw down. I did this earlier this year but i had to ask for this option and told them that these were my terms. I dealt with PTSB on north main street.