If you are expecting to use the granny charger much while travelling, it might be worth thinking about longer cables and weather-proofing. I was worried about using domestic adaptors and extension leads, so I bought a
Commando charger and then picked up a 25m extension cable and heads with UK 13A, European Schuko and Swiss Type J plugs from a camping shop.
It's rated to supply 16A continuously, although it's only safe to do that when using a Commando socket directly. (The charger defaults to 10A and has to be switched to 16A.) The charger seems to cope with reversed live-neutral polarity which matters for some Schuko sockets.
It even all fits in the froot still leaving room for a 5m Type 2 cable.