In reply to sjc:
if you approach from Ogwen you can leave your stuff at the top as previously mentioned, most of the path up is on a tarmac road to the lake followed by an easy track and a short steep zig-zag section. You can then view the route from above. I abseiled in, one abseil to the terrace, pull your ropes and a 2nd abseil of a big block from there, retrieving the left kit as you climb up.