“I realise disco slippers are not going to be much use on the long walk to the top”
I dunno I went up skiddaw in mine a while ago, the studs wore down a fair bit though
I went up/down snowdon the other week, I reckon around half the distance (not height) is easily ridden (my mum rode about that far) with some more ridable with some determination/stubborness
A shoe swap would be a good idea if you have room, one swap and a 100 and bit metre up to the top of telegraph in SPD shoes could work
Unless you’ve pedals that sort of work with flat shoes, you might be walking a lot of it, like the initial road climb?
I found non disco slipper SPD shoes good to walk up in, but found the loss in stiffness in the sole got painful going down rangers (though with cageless pedals)