A week's resting (bit of cycling last weekend, and dog-walking (mainly on the flat) Mon - Thurs) has made not much noticeable difference.
On the positive side though, had a phone call with the orthopaedic surgeon which was much more positive than the video call 2 weeks ago.
The bone reaction is indeed just bruising, which will hopefully heal very gradually if not aggravated and given enough time - could be up to 2 years. It might not ever heal fully, but should keep gradually improving for a while at any rate.
He reckons I should be able to get back to a decent amount of activity if I take it very slowly.
He implied DofE expeditions should be OK with care.
Coming off methotrexate.
Text conversation with Ewan J after he'd had a look at the MRI scan (or report of it) also was fairly positive - definitely won't get back to the amount of running I was doing before, but ought to be able to get back to a bit of running at some point. He seemed to think it wasn't as bad as I feared.