I'd tell my mum straight away and let her handle it, I'm totally shit with money. Giving me 100m would be totally stupid, I'd do crazy things. Mum will be more sensible and sort out trusts and grown up stuff like that. So yeah, I'd say I'm in a syndicate with my mum, that way she can keep me on the straight and narrow.
She's doing the same thing with her will. My brother and sister get lump sums, mine goes into trust and things are more specified, so I don't go mad and spend all the kids inheritance.
I'd ask mum for what I wanted, a big house in the country with some land and stables, some horses and ponies, with a groom employed.
A chef, personal trainer (which means I need a big indoor pool, plus a sauna and jacuzzi), a live in masseuse and beauty therapist (and a float tank like they have at the parlour), maids for the housework, an overnight nanny for the kids when I'm ill, a PA for organising my life, carers who would be paid generously instead of the pittance I pay them now, private healthcare, a holiday home in Florida, a chauffeur because I can't drive, private schooling for the kids, music lessons for all of us (I'd like to learn the cello in particular). I'd write and publish my own books, just because I've always wanted to.
So yeah, mum being in charge would be good. Do would a financial advisor probably.