Join this group 
The Beer Garden CLub
Beer Garden
Beer gardens are great, and we love them.
The Beer Garden Club scour London on your behalf and let you know about all the best outdoor spaces where you can find a cold beer and somewhere sunny to sit. Perhaps even on some grass (not guaranteed, this is London)
The Beer Garden CLub members...
"You can get two for one on the rooftop bar "Elba" near Waterloo"