Any global tracker, eg https://www.hl.co.uk/funds/fund-discounts,-prices--and--factsheets/search-results/f/fidelity-index-world-class-p-accumulation. They don't vary much so pick a cheap one.
Global trackers hold assets in proportion to market capitalisation. That means that they all have around 70% of their holdings in the US (https://www.fidelity.co.uk/factsheet-data/factsheet/GB00BJS8SJ34-fidelity-index-world-fund-p-acc/portfolio). Whether this is what you want depends is up to you-
- some people think the US stock market is overpriced- yes there was an apparent correction recently but it's almost back where it was. Europe and the UK look much better value.
- some people worry about how much of the US market is in just seven stocks (MS, Apple, Meta, Alphabet, Nvidia, Tesla, Amazon) which are likely to move together
- some people worry about the Orange One and his tariffs and whether there is still more volatility to come
etc etc. On the other hand, plenty of people are happy with having 70% in the US. For one thing, it's done brilliantly over the last few years. Yes it's dominated by tech but that's just a reflection of the value of tech and how far it still has to go. And while Europe and the UK may seem better value, people have been saying that for years and it has yet to translate into significant growth.
So maybe we're at the start of a rotation out of the US, out of tech and towards more defensive stocks (like consumer staples). Or maybe not. If you think we are, you might prefer something VLS100- less exposure to the US and more to the UK. If you think we're not, a standard global tracker will suit you better. Or you could have a bit of both.
Anyway, tldr- there's something to be said for a global tracker. There's something to be said for VLS100. Either choice will almost certainly be fine as long as you are happy to buy it and forget about it.
Also if I was to choose VLS100 and then there was a huge dip/ crash - is the key then just to wait? and once recovered, move funds to VLS60/ 80 as approaching retirement age?
Yes, you just ride out the dips. That's why it's not recommended to plan to hold shares for less than 5 years. What to do in the run up to retirement depends on a lot of factors- do you plan to buy an annuity or to draw down? Do you have other sources of income? What's your attitude to risk? How much do you plan to hold in cash etc etc. Yes, you'll likely be moving out of equities and into fixed income/cash to some extent but what that extent should be depends on all sorts of factors.
The Meaningful Money podcast is really good on all this and I believe that one of the presenters has a book on retirement planning which I imagine would be worth reading (haven't read it myself but he gives good advice on the podcast)- it's too big a subject to answer on MN.