18, UK-Based - Potentially leaving £50k wealth management for S&P 500?

I’m 18, UK based. Just took control of a £50k+ portfolio I built from savings and side hustles (flipping golf clubs, designer stuff, bit of luck).

It’s been with the same firm my parents use. They’re about wealth preservation, not growth. Best year I got \~16% while the S&P 500 did \~25%. Fees are 1% + 0.5% platform. I don’t even meet their usual client threshold but they still want to keep me, which feels off.

My aim is long term: save hard, compound, hit my financial goal at 45. With steady contributions and \~7.5% returns after fees, it’s doable.

Thinking of pulling it all out and going DIY passive. Options:

* 80% S&P 500 / 20% Nasdaq (higher growth, higher risk)
* 70% S&P 500 / 30% global index + a few stocks (more diversified, less tech heavy)

I know people talk about an AI bubble but at my age I think I can ride it out.

So:

* Is all‑in S&P realistic for a UK investor long term?
* Is Nasdaq worth the risk or better to diversify?
* Any regrets from leaving wealth managers and going DIY index funds?

Not after hype, just grounded experiences. Cheers.