BA do VDB but obviously only in oversales situations where it suits them. 'Compensation' comes down to your personal negotiation skills, their degree of desperation and other pax' propensity to accept a lower offer, but it would usually include cash or voucher plus hotel/food as appropriate. Other offers, a guaranteed upgrade on the next flight for example, seem less likely.

Anecdotally, there's a vanishingly small chance it will happen for you, but of course BA do oversell and do get caught out from time to time. We've seen stories here of BA staff approaching people in the check-in queues with VDB offers.

Best strategy is to watch loadings as your departure date approaches and make your interest known at the airport.

Note that this is distinct from your rights under regulation EU261/2004 if you are involuntarily denied boarding or downgraded.

This google query brings up a few threads: "site:flyertalk.com british airways vdb amount"

hth