Firstly, congratulations on moving forwards with someone.
You don't say what your aims are for these portfolios, whether it is to create more income, reduce capital, or whether capital preservation for children is a priority or if the current IHT exempt status of the SIPP is important, whether you want to ringfence some assets to make sure they go to your children in future. Are you a taxpayer, basic or higher rate, how close to one of the thresholds are you, are the SIPPs crystallised, etc etc.
All these things and more will affect your decision.
If simplification is your only goal then there are a few Global Trackers available, ETFs or Funds, which would suit your needs and choice would depend on your broker and their fee structure. The diffculty is that having been a 'tinkerer' up to now then letting go is not easy - trust me on that, I'd be a lot better off if I could stop tinkering.
Personally I wouldn't go 40% UK, my old Zeneca Pension was over 60% UK 20 years ago, now it is mainly Global Fund as I just left it and the UK portion has underperformed compared to the Global portion.
Personally I have a ringfenced unsheltered chunk invested in a Global Fund that is automatically sold off each month at a fixed amount, the aim being to deplete it up to State Pension age. It has met the aim of providing a steady top up income, and has not let me liable for CGT so far, although the ERI will be taxable this year. In fact the only aim it has failed at is the "depletion" goal, where it is looking increasingly unlikely to dwindle by the time I reach SP. Still, that's nearly 20 years off, so there's time yet
The advantage of this is it is completely 'hands off', I went through an adviser to set it up with a negotiated fee, the platform and fund costs are low, and I regard it as a self risked annuity, except I can amend the withdrawal at any time if I need to.
This sort of thing might suit you, but without knowing what you want from/for the investments then it is difficult to make suggestions.
Paul