Can you imagine your numbers coming up tonight, falling asleep thinking you've got 120mil, can do anything you want in life, and waking up to find out you've won 500k or 1 mil, a nice amount, not terrible at all but you can buy a decent house in London for that, and thats about it.
I'd probably buy some property straight away, a nice but not insane place for myself/family, not sure where, tempted to go out for a massive mansion for minimal cost near a national park or something, maybe right on the doorstep, away from the world. Or something like, a 10mil place in Richmond type area.
Buy some buildings in London for renting out apartments as a long term investment, even if you ran out of money something like a 15mil apartment block, 14 apartments(several listed on that rightmove website) would likely generate 30 k a month after tax, which would hardly be a terrible sum to live off.