England & Wales home purchase: is an accepted offer legally binding?

Usually not. GOV.UK says an offer to buy a home in England or Wales is not legally binding until contracts are exchanged. Once contracts are exchanged, the agreement becomes legally binding and pulling out can lead to compensation or other consequences. Official source: GOV.UK buying a home and conveyancing guidance. Guide: https://getinstantlaw.com/property-buying-selling/contract-problem