Hi Lynne
George Garside does indeed run slow sessions at Sidmouth, usually 2 or 3 in the week, around late afternoon. In previous years they were in the Rugby Club, and last couple of years in St Teresa's Hall (just beyond the old Post Office and the Radway) They are to be found in the Working Programme. Tunes mainly in G and D and generally at a playable pace. Very popular, loads of folk and all sorts of instruments! As I am learning button accordion, it's very good for me, if not for people around me!
In Edinburgh we have "slow session" classes at the Scots music group at Boroughmuir High School: these are run as evening classes with a fee - check out www.alpscotsmusic.org: on Wednesdays at 9pm we decamp to Bennett's Bar, near the King's Theatre for a further slow session with Nigel Gatherer (for the cost of a drink only!) I believe there are other slow sessions around Edinburgh: check out www.albafolk.co.uk for lots of stuff in the area.