I've been watching this take shape in the last couple of weeks or so, as I work just round the corner. 
A disused plot of land in Union Street SE1 will soon be the site of a pop-up garden with a medicinal theme -  ' a community built landscape of reclaimed timber, salvaged materials and donated plants. Summer in the Urban Physic Garden will be a festival of talks, workshops film screenings and events.' 
And this is the bit that caught my eye: 
"A decommissioned ambulance will become the kitchen of Rambling Restaurant, serving up a changing seasonal menu featuring homegrown herbs, leaves and vegetables.' 
Opens 11th June at 100 Union Street, SE1 - more here: 
http://www.physicgarden.org.uk/