Thanks for all the useful information.

I usually fly from NCL to pick up UA flights but I am so hacked off with picking bags up and re checking in in LHR so I thought I might try this route on a single booking ref/ticket. Bit more of a drive but hopefully less stressful.

As to lounge access, I had heard a rumour that dependent children didnt count as 'guests' but of course at what age does a dependent child stop being one? I will ask and see what the response is.