Hi Toby
You're method is not the easiest way. The way I did it I got the good break by the 50 for 5 chains and got my left foot on a big polished edge, then did a big rockover out left, bumping from an intermediate on the way to a pocket/ slot for the LH. Then you match feet on the polished edge and put your LF in the eye as a heel toe cam, then clip - a bit bold but totally fine (don't bother clipping at the 50 for 5 belay, way too strenuous). Then I got a small 2 finger pocket with my RH, moved my RF to a good smear on the slab, then matched in the pocket/slot (quite tricky, only room for 6 fingers in total). Go out left to the Ashes LH sidepull then get RH on normal Ashes sidepull then take LH of the cam and your in the Ashes. You're not allowed to step down and rest in the eyes but can use it for your feet. Hope this helps!