Managed to get my bike sort of working after replacing the rear axle. I've got some issues with the cones, but it's just about rideable.
Went riding in the Wildpark in Grafenberg yesterday, and on the way to the trailhead, passed an abandonned commuter bike. Inspected it and it was missing a front wheel and brakes, but with a bit of work, it looks useable. Could be perfect for riding to work on. Unfortunately, it's pretty old so none of my spares will fit, but I'm quite looking forward to restoring it.