I see you have no US forces in-situ in your scenario, so it seems like this is purely a thought exercise as in reality it would be very tough to come up with a realistic scenario that the US would not be involved in. There were US forces all throughout Europe in 1946 and I don't think they would just sit there while hordes of Soviet forces came streaming in...
I agree that the land side would quickly go Soviet, but they would lack the capability to easily reach the UK. The UK would dominate the maritimes.
I do think that the B-29 "Washington" lending would have been expedited, with special cargo....