^^^^^^^^^^^^^^^
This, a thousand times this.
I've been travelling along this road for many years, and I've read around the subject a fair bit. A low cost passively managed fund will outperform the vast majority of Active fund managers.
When I was working I saved into a Cash ISA and built up a "retirement fund". I'd invested in a variety of shares as well over the years, not great amounts but enough to get a feeling for the ins and outs of share trading and some of the pitfalls thereof.
When I did retire I switched the cash ISA into a Self Select Stocks and Shares ISA ( you choose your own shares and how many of each)
The (15 or so) Companies that I invested in were all FTSE 100 , and spread across various sectors so as to spread the risk of any one sector falling out of favour.
I left the Portfolio alone wherever possible, and let the dividends build up before taking lump sums from the dividend "kitty" as and when I wanted to pay for a Holiday etc.
I also invested £1000 into a Vanguard Life Strategy Fund, as mentioned above by
@alicat , but in my case a Lifestrategy 80 ( the numbers on the end refer to the ratio of shares to Bonds, so, for example the 80 Fund invests 80% in Stocks and Shares and 20% in Bonds, Bonds being seen as as safe and secure as it is possible to get)
The Lifestrategy Fund was chosen to act as a benchmark against my own share picking strategy and over the years it has outperformed almost all the shares that I chose. ( Unilever being one off the few notable exceptions)
Hindsight is wonderful, even after the recent crash I'm still less than 1% down on my original investments overall, but if I'd just chucked the lot into the Vanguard Fund I'd still be ahead, and with non of the work in analysing and choosing individual shares.