If you have a look on Flight Radar (nerd alert!) there are plenty of go-arounds happening at Gatwick this morning. The Cathay Pacific flight from Hong Kong has attempted to land at least twice now.
I'd imagine the same would have been true at Heathrow earlier too, albeit the squall line has passed through there now.
The wind's still whomping along here (it sounds like repeated "thump" noises as it bangs into the upstairs of my house) and I suspect that'll be the case for a couple more hours yet: the squall line is now over central London and moving slowly eastwards (slowly compared to Ciara, anyway, more like 50mph than 70 or 80 mph).
There have been a couple more brief power cuts, but it's still on for now. My postcode is showing as being without power on the UK Power Networks map, so I'm lucky!