With £100 million? Gaawd.
Buy houses for my mum, dad [separated] and myself, including one or two abroad [I'd like to have one in NY, USA and perhaps Australia, but only apartments really...that I can stay in whilst on holiday. I wouldn't need 5 bedrooms or something like that

].
So that'd probably be £20m in total...with decorating and other stuff too.
Then learn to drive and buy a car [and get my mum a new one too...it's a crappy old Rover atm.]
Then take my friends on loads of holidays

I'd give them money but I have too many close friends to give like £1m each to, lmao. Perhaps £500k each to...I think 10 of them. So that'd be £5m.
Donate roughly £10-15m of it to charity, and save the rest to live on in luxury

[which would be roughly £55m

]