Step 1) Make an appointment at Lavenders with "coco"
Step 2) Go to said appointment with £20 extra in your pocket. Relax. Get naked (on the table in the room, not at reception). Ask about extras up front, they won't be offended. Worst they say, if they've not met you, is "no".
Step 3) Repeat steps 1 and 2 then once you've met her a couple of times and she knows what you're going there for ask about tantric.
There's not all that much difference to be honest, but she's very, very good.