Usually anything I book comes after months of deliberation and research but today something came over me and I saw some bargain theatre tickets and a central hotel room - cost just over £100 for both for three of us, which to me is a massive bargain so I booked it all.
Now I realise that I haven't actually stayed overnight in central London for over 20 years and never with a car/children 
. Usually I drive down on a Saturday and park at Stanmore for a pittance, stay all day and drive home. But that obviously won't work on a weekday. Other times we've stayed less centrally in travel lodges with carparks, but I've booked non-refundable central hotel now, which actually will be good with evening theatre, but, of course, doesn't have parking and, while I think there is NCP quite near I assume it will cost a fortune and result in us sitting for hours in traffic/getting lost finding it.
Does anyone know of outside congestion zone carparks near a tube I could use and safely leave car overnight? I have looked at the train, which would be another £100, including the cost of a railcard. I'm happy to pay that if needed, but to be honest I like the flexibility of going by car. I'm not trying to be cheap - I just don't want to drive in the centre anyway but like not being restricted to train times.
Any advice would be great.