My local club is Eden Park,
www.edenparkraceway.com we race the first Sunday of every month, there is Stotfold
www.stotfoldmcc.co.uk you can find there schedule on their website, both of these clubs get a good number of drivers and an excellent quality of drivers. Both of these are outdoors, indoor a good club is Worksop
http://www.oople.com/forums/forumdisplay.php?f=49
look in this thread, warm and dry racing with a large numbers of racers.
I am sure you will be welcom to any of these meetings, and you can race on the day, but a BRCA liscense is best, you can get it at
www.brca.org
Where are you coming from and how long ya gonna be here???
There are 3 big indoor meetings, but they all are before you get here.