Before you splash out on a Novoflex adaptor, try a cheapie from China via ebay. The Contax/Yashica mount to M4/3 adaptor is very simple and while the Novoflex adaptor is superb - I upgraded to one recently - it is overkill for just trying the lenses out.
The adaptor suggested by Alan looks fine. I've bought several adaptors from here. Delivery should be quick from either seller because the adaptors are already in the UK.