Clois: Welcome to the Club! And, thank you for your support. A lot of us who have been around Sunbeams for a while sometimes speak in shorthand. "SS" is a reference to Sunbeam Specialities, the preferred new parts vendor for many of our members.
http://www.rootes.com. You will also see people say to "Give Rick a call". That is another reference to Sunbeam Specialities. The other main supplier in the US is Classic Sunbeam Auto Parts (aka CS to "Curt").
https://www.classicsunbeam.com They are both very reputable and well-respected in the community and you will not go wrong with either of them. If you start searching our archives (a very good thing to do as you familiarize yourself with your new car), you may also see references to "VB". This was "Victoria British", who sold some Sunbeam parts, but primarily parts for other English cars. VB's parts were frequently not as good as what we can get from SS or CS, but they sometimes had things that were otherwise unavailable. However, VB recently sold their British inventory to Moss Motors, who currently covers everything but Sunbeam. Whether or not they pursue Sunbeam business long term is at the moment somewhat open. It would be nice to have a third choice, but it is also good to support both SS and CS whenever you can.
I suspect most, if not all, of what you will need will be available new from SS or CS, something I didn't think of when you contacted us on Facebook. However, if, after studying their online catalogs you find something you need that is not there, you will almost certainly be able to source whatever you need from one of our members.