As Joe said above you can get an increase in your 20% tax band of €9,000 which is worth €1,800 over the course of the year
Assuming that your husband will work at some stage in 2015, you cannot therefore take any of his tax credits for the 2015 tax year as he will need it to shelter his own income
So total tax saving = €1,800 which works out at €150 per month
You would also be entitled to some tax back for the 2014 tax year which you can apply for in early 2015. At a very rough guess it should be around €1,400 I think. You should ring Revenue in 2015 and inform them that you were married in 2014 and wish to be jointly assessed from date-of-marriage and they should sort it out for you.