In the UK, there's a web shop dedicated to the Oly Trip. Of course the 35RC also has the same filter thread. Although I couldn't see any metal hoods or ND filters, it may be worth keeping an eye on the stocks from time to time:
Rather than trying to hunt down accessories in such an unusual size, I think you'd find things much easier if you bought one or more step-up rings, say in 43.5-46mm.
B&H sells them fairly cheap and after that you'll have a much wider selection to choose from.
Nice camera by the way.
Derek.