Reporting back. Luckily no issues at all with flights, looked like LHR - NBO and return flights on every other day had been cancelled and we escaped! Flight dep T3 LHR which meant we could check out QF and CX lounges. We returned to T5 which saved us changing terminals for our GLA flight. We used the Arrivals lounge for breakfast and freshen up, definitely a good decision as Galleries North was packed. Luggage all fine, checked through both ways. Low lactose meal on CE flight not great - egg white omelette with spinach. CW much better with a very good fish en papillote main, lovely fresh berries and some other nice things (can't quite remember everything now and didn't take pics!). We didn't eat on the return as we'd had dinner before going to the airport. Breakfast was poor, not as good as CE standard breakfast, which was 3 choices plus croissant, yogurt and fruit - CW was yogurt with something that was supposed to be strawberry compote and granola, an Alpen strawberry and granola bar and a choice of a turkey and scrambled egg panini or a cheese and egg thing. The turkey option was inedible.
NBO airport was fine on arrival - I think we disembarked at 1something, very quiet and only flight, with fast luggage delivery. Returning was a bit more chaotic, priority check-in was pretty quick but long queues for anyone else.
Kenya Airways lounge was ok, busy and very hot. As noted above, there's a small number of showers - two in the ladies bathroom and I expect the same in the gents - hard lines if they're in use though, I heard a few people trying when I was using one. Food looked ok but we didn't have any, self pour drinks selection acceptable and staff were making coffee to order.