Driving from Caernarfon; Pentre Bach is to be found between the villages of Waunfawr and Betws Garmon. 

Come out of Waunfawr, past the pub then after two bends on the straight on your right hand side you will see the sign post "CAMPING BARN" (OS Explorer 17 531579).

Alternatively driving from Betws y Coed & Capel Curig:

Take the A4086 then A498 to Beddgelert. Follow the A4085 towards Caernarfon. 

Pass through two villages; Rhyd Ddu (3.5 miles) and Betws Garmon (5 miles). This village is split, continue past the village church over a bridge and past a row of cottages. Pentre Bach is then the first entrance on your left and is sign posted "CAMPING BARN".

Average journey times

Chester 2 hours

Holyhead 1 hours

Shrewsbury 2 hours

London 5 hours

For a useful map site try multimap.com