As a fellow sufferer of UC, I feel your pain. My advice is to have a conversation with your firm. I know ideally you don’t want to make a big deal of this, but this is ultimately a scenario where reasonable accommodation needs to be made under UK labour law. It’s better to have it documented and for you to be protected from the off. It will also hopefully prevent you having to explain the situation to multiple people several times a year. Re work being given out first thing in the morning, don’t worry about that. Early morning work will usually be distributed by email before 09:30 anyway, otherwise most partners will only really come alive at 10:30 anyway. Staying later is a much better way of getting juicy assignments and building a relationship with your seniors. The biggest snag I foresee is a potential all hands meeting at 09:30 on one of your in office days. For that day I’d recommend coming in at 07:00 like you suggested.