If he's working, even on an apprentice wage, and living with parents, he has a decent amount of spending money so doesn't really need access to lump sums unless he needs to buy a vehicle or invest in a business so he can afford to lock the money away, most of it at least.
With higher interest rates, and the trend away from BTL, it's unlikely that he'll miss out on easy money by not buying a house to rent out. However if his apprenticeship is in a trade, he could use the money to start a property development business, buying doer uppers, refurbishing them and renting them out, using an agency if necessary (and being a caring responsible landlord that even MN might approve of
). However that needs a degree of drive and focus to do that successfully.
If he's no real idea, he could keep back about £10k in cash and the rest put in a mix of short and long term products. Anything in cash will attract tax on the interest so it's good to be aware of that.
Unless he's really keen on the BTL or even buying his own property, so would want the money for that, he could put some of it into his pension (I think he'll be limited to 100% of wages) so that could take up around £13k per tax year - at this time of year it's always worth bearing in mind that you can 'double up' on allowances by putting the full allowance in now and the same again after 6 April next year. Same for his ISA allowance, cash for any money he might want to use in the next few years, at the moment, that guarantees a few % a year return, which can't be said for S&S ISAs, although these could be an option if he's no real idea what to do with the money in the next few years.
For cash savings, 1/2/3 year fixed products will mean he'll get a slightly better return and make it a bit harder to access the money. Seeing as he needs to use options that aren't taxable (although he has a £1000 tax free allowance on interest) Premium Bonds might be worth a look at - if he puts in the full allowance or a decent fraction of it, his payout should average close to the stated prize fund percentage.
With that amount of money at his disposal, he might as well open a LISA and put the full allowance in each year (£4k I think?) which he'll earn an annual bonus on, but the money that goes on here can only be used towards property or as a pension.
Anything that's not going into any of the above options can go into a decent paying instant access account so it earns a bit of interest, 5% is widely available.