You need to be speaking with Caradon Ideal, not Stelrad... Yes you can still get some parts for this appliance, but I believe it is now a reduced listing (Ie: Only a few of the bits)...
Your local parts center will be able to help out, contact HRPC (Part of Plumb Center Group) who will be able to obtain the bits, or your local plumbing supplier may be able to help as well... HRPC is probably your best bet for a fast supply but it depends on what you need.
Stuff like thermocouples have "universal" parts that can be fitted.
GasAid.co.uk
December 2006