Originally Posted by corporate-wage-slave

1) I think additional fuel costs are in scope over and above a single trip to the airport, this is under Right to Care. A taxi would be claimable.
2) What matters is whether BA offered a service that would leave no more than 1 hour before and arrive not less than 2 hours later. If there was no such offer then even if you don't travel at all you can claim cancellation compensation (this is different from delay cancellation).
3) Right to care is about what you need to sustain you, in terms of food, drink, comms charges, travel. So if by going home you minimise this then I would say that's a reason for paying point 1 rather than a reason to load up. So if you got the £10 vouchers - which we normally advise against accepting as per the Disruption Signposts thread - what happened next? If you went home and had a cup of tea then I guess you could charge for that, but this is all about what you did at the time. Comms may be chargeable, but it's free wifi in LHR. Perhaps parking?

This does illustrate the risks of splitting bookings, and as you have found, Avios bookings can be extra problematic. It's interesting the airport sorted you out, and I can see how they did this by just re-queuing your booking, but normally the advice is to rely on the Contact Centres. If they are non contactable then you can make your own arrangements, but BA won't make that too easy to claim.