London is crowded and an old city, so will not fare well during the coming shift which will be far more severe than prior shifts. The British Ils in the past have received jolts, to the extent of tumbling some of the Stonehenge massives, this will be at least as strong. Add to broken buildings and bridges the issue of old plumbing and seweage, and you have a mess. To the extent that London is above 700 feet above sea level today, it will remain above sea level after the poles melt. However, crowded with desperate survivors, starving, this place will not be any more pleasant than other cities during the immediate Aftertime. Best to locate to rural areas prior to the shift, and plan on ocean fishing as a prime food source.
In that the European tsunami is anticipated to be half the height of the pole shift tides, and washing through the English Channel at a height of 100 feet or more, what can be anticipated at this time for the lowlands of England and the eastern coastline along the channel. Rushing water, under force and moving rapidly, not only floods, it bites. Where the European tsunami might not rush all the way into the lowlands in England's interior it will certainly rush into any lowlands along the eastern seaboard and force up the Thames River to roil London's docks. This will not be a flood, but a scourge, tearing away buildings and docks and all unfortunate to be in its way at the time.