Don't know if it would help, Liz, but I was just in the local Aldi store. One of the specials this week is a set of laptop computer accessories for about £15. All of them are USB connections, and one of the items is a standard layout numeric keyboard as a free standing pad.
If your work set-up would allow it, it would mean that you could position the numbers to suit whichever hand you needed to use.
Quack!
Geoff.