It looks to me like you're way short.

Any one-way booking with Avios in the US would require a minimum of 7,500 Avios each, although you might have some Avios & Money options.

And as mentioned, please don't waste the hotel points. Conversion rates are horrible.

The other thing that occurs to me are the VS flights out of Manchester. No LHR Clubhouse but you might find upgrade availability from there.

Otherwise 500 quid is a good fare and you should think about grabbing that. Even if you had enough miles it's going to cost at least half that in APD and surcharges to book an award of some kind.