There is a car park near the Sun Inn, I think it's about £3 per day which at busy times has a parking attendant. Last time I was there he was friendly and helpful. Fills up though as its much cheeper than the other car parks in the village.
Alternatively there is a lay-by big enough for 3 cars on the minor road near a + jucntion. Follow signs to Howtown from the centre of Pooley Bridge to reach a + junc (right to Howtown, left to Penrith, straight over (T) heading up towards Askham Fell.
Go left at junc towards Penrith, lay-by 50/100yrds on left. Might not be as secure as the car park?