The Samatha Trust is a lay Theravada Buddhist organisation, offering meditation classes for beginners and advanced practitioners, as well as holding various other events such as group discussions, Dhamma talks, puja (devotional ceremonies), etc. I have been visiting the centre for over a year now, and the atmosphere is great. The teachers, helpers and meditation students are all really nice, and everyone is welcome, regardless of religious belief or lack of it -- you don't have to be a Buddhist to come to the centre and meditate.
The practice is focused on Samatha meditation, Samatha meaning calm, serenity, or tranquility.
Although the teachers are lay people, often bhikkhus and bhikkhunis (monks and nuns) come to the centre to give talks.
Overall, it is a great place to visit if you are interested in Buddhism or meditation.