Dunno what car hire is like at Welshpuddle (aka Trallwng), but might be worth giving them a bell.
Or give Whirly a bell - a bit of helicoptering might be good for a laff.
To be honest, I'd drive the whole way from darkest England - probably take you 4 hours each way. I suggest a route that is relatively fast, clear, and avoids the caravanserais of the A5. Going via Llangollen, Corwen, and the road to Bala is NOT my favourite way.
Instead, go Shrewsbury - Nesscliffe bypass - Knockin (stop for provisions at the Knockin Shop) - Llangynog - over the Berwyn Mountains to Bala, turn left at the lake and there you are.