Join a cross country ski club
It's a good idea to join a Snowsport England affiliated ski club, not only do you meet other like minded people, but clubs often devise good value, informal ski trips and rollerski courses for members. Bear in mind that they're run by volunteers so you'll have to do a little more work yourself to participate in trips.
We belong to London Region Nordic Ski Club which organises a great programme of events and rollerski training courses throughout the year in the London area. There others around the country listed on the Club's website.
Snowsport England is the governing body for all snowsports in England. It organises skills development courses on roller skis and on snow. These include the Nordic Skills and Multi Activity Week at Kvitavatn in Norway every season - in 2010 it will be held from 4-11 April.
I've attended this twice and can thoroughly recommend it if you want to improve your technique on a fun, active week. Read my article about the 2007 event which appeared in Snowsport England's magazine, The Piste.
Snowsport England also offers proficiency awards and instructor qualifications for ski-ing on snow and roller ski-ing - I've qualified with them to teach both disciplines.
BMCCSA is a national club for anyone interested in cross country and roller ski racing. With membership you get an irreverent newsletter 3 times a year which also contains some useful, serious articles and you can enter the Masters World Cup [World Championships] races for Great Britain.