Hi Joe,
Yeah you should be a BRCA member to race at the meetings. I am pretty sure you can join the BRCA any time though although you might have to do it off your own back. I am sure there is a period towards the end of year that you buy BRCA membership and get X amount of months for the price of twelve.
Go to
http://www.brca.org and find the contact details for Jacqui Rowcliffe she will be able to tell you better than I will. I am sure the BRCA make provisions for people joining late in the year though.
Rob