Londonist did a twelve-part series exploring London's pagan history, artifacts, and connections, but unfortunately their Youtube channel never collected those videos as a playlist. To rectify that, well, here they are. There's plenty of inspiration to be had in these brief tidbits.
Episode 1: Old and New Pagans
Episode 2: The Stanwell Cursus
Episode 3: Shepperton Henge
Episode 4: The Dagenham Idol
Episode 5: A Bronze Age Burial Mound by London Bridge
Episode 6: Springhead
Episode 7: The Temple of Diana
Episode 8: The Mysterious Maypole of the Strand
Episode 9: How Did Druid Street Get Its Name?
Episode 10: Primerose Hill - Tamer of London
Episode 11: The Obelisk of Ra
Episode 12: A Strong Brown God