God how rich would I be now, if someone had given me £5k at 13 and my parent knew how to invest in a fund...
I won't give you chapter and verse.... But this is what I've done for my godson and my two daughters...
£x in an ISA for them....
Bought Fundsmith Equity Acc or Vanguard Global with it...
Ignore Bonds, Metals, Commodities, Bitcoin, and do not hold Cash...
She has time on her side... If the last 60 years are anything to go by, it will get anything from 12% to 20% per annum and earn between 50 and 100% every 5 years... Any lower than that, review fund choices... Any higher than 100%, consider diversifying too... eg. take excess profits...
Time is the critical factor in wealth generation with equities, and she has an abundance of that, if you can convince her not to spend it as soon as she gets it... But rather, get her to start putting in £25 a month in as soon as she can... There's a whole set of market theories that boil down to investing £25 a month (that's usually the minimum on the better investment platforms) called dollar cost averaging, that I think everyone should do... Honestly, knowing what I know now... So simple to be a millionaire, if you have time and £25 a month...
Anyway good luck getting to that first million, this is a brilliant first step.. :-)