I walked up Honor Oak Park on the One Tree Hill entrance side recently with my young children and I agree, it's quite intimidating.

Maybe a mini roundabout at the top of the hill by the school to slow things down and help traffic flow?
Maybe a full width round-top speed hump in two places between the top of the hill and the zebra crossing by Devonshire?
Maybe the zebra crossing by Devonshire could be on top of a speed table on the downhill side?

Here's what it could cost though