Modern bistro all on one level
The Green Room is a bistro restaurant on Upper Gorund right behind the National Theatre. It is in a modern building with no steps or even slopes from the street to the tables, which contain props from National Theatre productions.
Transport & Parking
Between Waterloo and Southwark underground stations, both step free access from the Jubilee Line. Don't know about parking, but is part of the National Theatre who are normally quite good at arranging it.
No steps or slopes at all. Toilet wasn't well signposted, but that did prevent others using it.
The loo is to the left of the entrance. Spacious, but with a bit of clutter from baby change stuff around the toilet itself. Red cord was tied up, and soap dispenser was a bit high.
Very friendly, but didn't have to rely on them for help.