Theres Genericlan thats in Padworth - Near Reading.
www.genericlan.net
The I-series which has for the moment moved from Newbury to Coventry.
http://www.multiplay.co.uk/eventdiary.asp
Multiplay also hold a much smaller lan -Stratlan which takes place in Stratford-Upon Avon, thats not too far north.
http://www.multiplay.co.uk/StratLAN/