Perhaps the idea of putting larger format bottles on the list might be worth exploring?
If the place already has an established wine menu, then I can well imagine 5 or 6 quality beers in 75cl bottles fitting in well; a large number of couples/groups are willing to throw down between 15-25quid on fairly mediocre bottles of wine in many city centre establishments, so there's no reason why large format bottles of beer (which can definitely be sold around the 10-12euro point including a decent margin)wouldn't shift at a fast pace too with a bit of encouragement from knowledgeable staff.
Off the top of my head, here's a few 75cl bottles available on the Irish market:
The Chimay range (dubbel, tripel, and quadrupel)
Westmalle Dubbel & Tripel
La Trappe Quadrupel/Dubbel
Brugse Zot Blonde Ale
Tripel Karmeliet
Kwak
Duvel
La Chouffe, Chouffe Houblon IPA/Tripel, McChouffe
Meantime IPA
Sierra Nevada Wet Hop IPAs (65cl format)
De Ranke XX Bitter (excellent hoppy Belgian ale)
Plenty more out there too. All of the above go wonderfully with a variety of different foods - hope that's of some help!