Only 15 miles outside of London is Mayfield Lavender Farm. Its 25 acres are open to the public throughout summer. I took my camera for a visit. It is a lovely field which smells wonderful. The key thing for me was that you can get there by public transport from London. Despite still being within the M25 it feels like the countryside and is a great antidote to London.
They have three different types of lavender growing so a large patch is always in deep purple bloom from the end of June to the beginning of September. You can wander happily through the rows of lavender sit in the sun, have a tracter ride and sample some lavender ice-cream. And of course you can buy organic lavender and lavender products.
Picnics are not allowed but you can buy food there ans sit on tables that are set up. There also is parking on the property is you are driving. Entry is a mere pound and makes for a pleasant afternoon in the sun.
For the photographer
Professional photography, portraits, etc, is charged at £50 a session. The day I went there was a bride being photographed amongst the lavender. It would make for stunning shots. Otherwise it gives oportunity for close-up and macros of bees and sweeping landscapes of rows of lavender.
How to get there
Get to Croydon West by the overland train. From there catch the 166 bus towards Barnsted and get of at Oaks Park bust stop.