Depending on Business Class redemption availability on the date that the OP will be traveling, he might also consider flying into EWR or JFK, taking the train to Penn Station Manhattan, and then taking one of the several daily Amtrak services from Manhattan to Albany/Rensselaer station. The train ride typically takes just 2.5 hours, and is usually reasonably priced. Plus, the OP would save 7,500 Avios. In my mind, that would be a better alternative than flying LHR-IAD, and then having to connect to DCA-ALB.