In reply to Glyno:
As you come off the A66 take the B5289, (brings you in past the petrol station, over the bridge with the pencil museum on the left). If you take the first right after coming off the A66 before you get into keswick theres a dead end road that leads to the suspension bridge to Portinscale. Theres usually the odd camper van parked on there. Bit of a walk to Keswick, but out of the way.