To bring this thread up to date, I had my one year post-op review in September. Surgeon said xrays look fine so he doesn't need to see me again (but to keep in touch). This came after a summer of parkrun improvements and a couple of short local fell races. No problems with the new hips, just me being a bit out of condition. I then set a goal of the LDMT but retired after 4 checkpoints, not because of the hips, but because I'd done a long walk the day before and hadn't recovered. So as a consolation I entered today's Langdale Horseshoe, and finished this time - not fast but it felt great to complete it.
And with that I feel that I've reached a big milestone in my recovery.