Interesting one, are you are returning to Ireland to live in this house..?, if so you will need a good mortgage broker, a firm cost analysis of the building costs perhaps done by a Quamtity surveyor and often insisted upon by the lending institution, a professional valuation addressed to the Bank and confirmation of employment status in Ireland for the future, generally you could get up to 3 times your confirmed gross earnings subject to repayments not exceeding 40% of net monthly income, the site appears valuable but are there any conditions in the permission which limit the build to yourself alone, if so the site value is questionable.
If you want to build a house to rent while you continue to live in Canada then in my opinion you have little hope despite site value and savings history., I guess more information would help in forming a more indepth response, Good luck to you.