Bob,
If you go to the 'douglasmotorcycles.co.uk' website, click on register (on the header bar) and fill in your details, admin will then issue you with a password that will admit you to the members only areas. Once logged in, you can change your password to something that you find easier to remember.
On the subject of spares - the prewar list shows items that are normally stocked. The postwar list is of all known part numbers - not all of these are normally in stock, so it may be necessary to enquire if an item is in stock before actually ordering.
Regards,
Eddie.