Pembrokeshire is in south Wales.
446.83 kilometres (277.65 miles)
Wales is part of the United Kingdom and it is north of the equator.
Its approximatley 3.5 hours - If in Mid July add an hour to account for Traffic in Builth Wells
Impossible to say without knowing if you're going by foot, bike, car, or train.
Why ask this on here? Look on a fcuking map!