I did quite a bit of riding there last year and was surprised at how easy but satisfying it was.
Eastern bit, not sure – it looks like more short sharp climbs, which is energy sapping. However there aren’t too many of those it seems
You will notice them – the climb out of Wendover, the climb up from Whiteleaf (walk if you’re sensible), the hideous long drag in the wooded ditch which isn’t that steep but has a surface of leaves, loose dust and large rocks/branches, Barbury Castle, the climb up from the curry restaurant etc.
Add in the mileage and the pounding you get from dried hoove prints and I’d suggest you don’t enter it too lightly. I’d done a lot of miles, trained specifically for it and was on a short travel FS – it was still hard!
Taps I used were
Aston Rowant – nature reserve
Wendover Church
Sparsholt (I think) it’s on the left just at the end of a track with a racing trainer advert
House – just by an A road crossing on the W end