In what airspace may gliders fly in clouds in the UK without an IFR flight plan and without contacting any air traffic control facility? In what airspace may gliders (sailplanes) legally be flown in clouds in the UK without an IFR flight plan and without contacting any air traffic control facility?
Also, how high does this class (classes) of airspace typically extend in areas where cloud-flying in gliders is commonly practiced?  (A general range is fine--the intent is to allow the reader to compare and contrast with Class G airspace in the US1, which rarely extends higher than 1200' AGL.)
Footnotes--

Cloud flying in gliders in the US is rare for several reasons, including the fact that the pilot would be required to have an instrument rating in airplanes (see FAR 61.3(e)(3)).

Some other related ASE questions and answers of interest--
Can you fly a glider in a cloud on primary instruments?
Can you fly a glider in a cloud on primary instruments?
Can you fly a glider in a cloud on primary instruments?
&quot;Teaching Instrument Flying&quot;-- Instructor Training Notes-- Dartmoor Gliding Society
&quot;Instrument Flying Training Notes&quot;-- Dartmoor Gliding Society
Cloud Flying endorsement webpage from Motorglide.co.ok
Broadly speaking, the UK is Class G, excluding airways and terminal areas, from surface up to FL195.  Can hop in your aircraft and fly IMC without talking to anyone to your heart’s content