From latest GASIL:
GPS Jamming
As described in AICs, the MoD will carry out GPS jamming trials during the next
few months. The fi rst will be around the Sennybridge training area (D203 in mid-Wales) between 7th and 18th September. There will be another over the sea South of Cornwall on 9th & 10th September, and finally another in East Sussex on 14 & 15 October.
http://www.caa.co.uk/docs/33/srg_gasil07of2009.pdf
Last one is near Bexhill according to this
Safety Alerts