I'm Irish and I live in Ireland.

I think you are mistaken if you think you can arrive at some small town in Ireland head to the nearest pub and expect readymade nightlife just waiting to happen. Life in small town Ireland especially midweek can be as dull as anywhere else in the world.

You don't need a van to lock your bike into every night. It will be perfectly safe at the hostel.

Forget the van, come to Dublin (I'm a Warmshower host and I'll host you provided you don't hire a van), then get a bus (cheaper than train) to Cork and head southwest to west Cork and Kerry, then up towards Galway.
Get the bus back from Galway to Dublin and fly home.

If you just want to party and drive a van you'd do better to stay at home.