Smallest worthwhile S&S ISA

[MessySurfaces]

So, both my kids have about 6-7k in child ISAs, earning 3.5%. They are unlikely to add very much over the years. They are both small still (1 and 5!) so I know I should be investing the money, but I'm scared! I had cash savings as a child, so I feel they should.
I was wondering about doing half and half cash and S&S- but would lots of 3-3.5k be too small for that to be worthwhile?
I've just opened a nutmeg lisa for me, no clue where would be good for child S&S isa!

For investment horizons of 10 years or more, you should really go for a stock and shares ISA and let compound interest work its magic.

I use interactive investor for me and the little one's Junior ISA: the same fee covers the account of both. Have you tried asking on moneysavingexpert?

Platforms like Nutmeg tend to charge no fixed fees but higher % fees, whereas with brokers like Interactive Investor it tends to be the other way round. The former tend to be convenient if you have little money invested. Bear in mind that with a broker like II you can invest in ETFs which charge as little as 0.07% per year of management charges.