I know nothing about RE, but what kind of % were you looking for? You can margin a short on any stock and double your money if housing tanks.
With these guys, cityindex, you can bet on UK suburb prices. Cheers http://www.cityindex.co.uk/spreadbetting/Finance_SpecialMarkets.cfm?property=1
what, are people going up and dump their houses and live on the beach? relax, it's a joke. with a point.