BMBO National Championships weekend this coming Sat/Sun in Lorton Cumbria
http://www.bmbo.org.uk/calendar/details.php?event_id=332
which is exactly like the Polaris but without having to carry bivvy gear
BMBO also have a Facebook page, just search BMBO & press like
I think far too many people dismiss our sport without actually trying it, it can be a fun day out or a full blown competitive event, challenges the grey matter as well as physical ability & gets you riding in different places. The NYMBO events are run by the same course planner who did the Polaris but there is only one left this year. Winter series starting in the Peak District soon.
Hope this helps