As far as training days go,i know that BARC have got one on 1st march at Thruxton.
and i do believe BMMC do that session aswell,i do recall Mr s Green waving a flag at post 2 in assistance.
But check
http://www.volunteersinmotorsport.co.uk/ and you will find dates on there.
Plus you might get some dates during the season.
but it`s not a must to do a training session yet.
just gives you a better insight to what you let your self in for....