There are significant services between the US and UK (as well as other European gateways). Many people flying because they meet one of the many exemptions.
But, none of that helps OP as he apparently does not have an exemption.
Remember that it is not simply a cancellation by BA but a substantial change which would entitle OP to a refund. I would wait until 2-3 hours prior to scheduled departure. Last minute weather or technical problems still happen and if either one of those results in a substantial delay or cancellation, OP gets his refund. If not, at T-2, he gets his "funny money" for future use. Nothing but upsides in waiting.