How to fly IFR during the Olympics?
They are imposing a strict slot allocation system for all IFR procedures, though it should only be for procedures which connect to flights into enroute CAS (London Control).
The obvious solution - Z and Y flight plans - is going to be banned.
The bizzare thing is that e.g. a Z departure will be banned even if the VFR-IFR transition is outside UK airspace. In reality, e.g. departing the s. coast VFR, one only just reaches the ~FL075 base of CAS (SE piston, not a bizjet or an F16) by the time one enters French airspace, and even in a jet this would be no big deal, so I don't understand why Z is banned outright. Maybe it was the only way they could work it as a Eurocontrol restriction.
The upshot of this is that a lot of IFR traffic will be flying on V flight plans, probably filed on the Eurocontrol routes, and on the way out of the UK will be asking for a popup IFR clearance. This will probably work in France, where the lower airspace system is continuous FL065-FL200 and you can fly the same routes VFR FL065-FL115. But it will be "fun" elsewhere. But it will be hard on the way back to the UK, coming from possibly much further out. I would bet most countries won't entertain it.