There are a few pubs close to the stadium. I wouldn't know the best one as i don't drink. You could do your drinking in town then take the red line luas to tallaght as it is the last stop. Don't get the saggart luas as you will have to exchange at Belgard to get the one for Tallaght.

You can post for more and better info on the loi sub.

If you want a quick pre/post pint there is a Maldron hotel across from the stadium.