Thanks for the replies folks. Not too worried about uncoated lenses especially with B&W. Have had a lot fun in the past shooting a Zeiss Ikon Nettar with B&W film with zero issues.
At the moment, tempted by the Contax as it appears in nicer condition and comes with a six month guarantee. Need to speak to the retailer about if first and then search to see if there's anyone in the UK who services them first though...
Originally Posted by Archlich
A Canon P is much easier to use , much cheaper and still very nicely built.
Funnily enough, a Canon P is also an option, with a Canon 50mm f1.8. It's about the same price as the Contax IIa and Leica IIIa though.