Trying the Voigtlander 17.5mm

I'm tempted by the Voigtlander because I love shooting low light shots without a flash, but I've never used a lens like it before (heavy, only manual focus) or spent that much on a lens. So, I'd like to try it out before I buy one. I'm in the UK and have never seen it in a retail camera store, although it's on eBay a lot. Ideally, I'd like to have a weekend to try it out too, not just a few shots in a store. Does anyone know of a store with a good returns policy in the UK for lenses that would stock it? Alternatively, can you rent one for a week from anyone in the UK?