Check your wallet........are you SURE you want to race
OK - on the MSA site (msauk.org) click on "Getting Started" in the toolbar at the top and away you go.....
The "Go Racing" pack probably won't tell you much you don't know, and in all honesty in my experience the ARDS test won't either - maybe if you attend a course its better
- but its the hoop you have to jump through.
As for where to start - a single make series might be a bit intense for starters - the racing tends to be very close, but its largely up to what you fancy....you could buy a prepared car for £2K upwards and compete in something like CSCC tintops or future classics - a friendly club offering good value - but no doubt plenty of others will have their recommendations.
Could be worth trying an arrive and drive hire package before deciding which way to jump?
Whatever, welcome to the other side of the bank, and enjoy!