Soldato
I used Just Park and parked at Hammersmith. Got the tube into London. Parking was £8 for the day.
If you’re coming into London from outside the M25 and don’t mind a short tube ride to get into the centre of town, parking at a Tube station outside of the Congestion Charging/Low Emission zones is a vert smart idea. Avoid the peak periods and you’ll be fine.