A lot depends on how much you have, say you have inherited or saved up £100-200k, then going to be looking at a different type to someone with £20k or someone who is high net worth.
It is generally recognised that paying for managing is only sensible when over about £70k of assets or savings (otherwise the annual fee isn't really covered by the extra they can gain by being proactive with investments). Active management is keeping eye on market trends and moving selected items, to maximise returns, they do it, rather than the periodic advise where to invest (and just sits there even if that investment is no longer as good)
At its simplest book a financial advisor for some guidance, as long as they are FCA regulated then there is a level of protection and professionalism. (Can check not be barred on FCA website).
Some work alone, others work for firms, with firms they often have specialists in pensions, mortgages, investment etc so need to be speaking / meeting the appropriate person. Obviously these small-medium size firms can offer specific or more complicated advise than an individual who deals with more general mix. Unless you have big wealth no point in going to massive firms because won't really get the service, and high fees.
We (wife and I) have one, originally they gave some advice to a group at my wife's then work when there was round of compulsory redundancies and getting redundancy money. That individual has now retired, but we have stuck with them as seem to have good team.
Over about 15 years (and normally have a meeting once a year, or every 2 years) have checked how we feel about risk, and when we might want to draw down money etc, and invested accordingly. Some years we have added funds. They have also boosted the growth by advising us of pension and tax breaks etc that we wouldn't have known about. (things like put money in pension, and also save on child benefit taper etc). We are now in our early-mid 60s, drawing down a bit each year because retired early (get company pensions, but not yet state pension), so need the drawdown to cover lack of state pension.
My personal advice is try and find a firm that has been going a few years, and has grown, not too flashy, but with people who seem to have experience. Don't be afraid to go a few miles away. Ours is near St Albans even though we were in SW London when it started, and we are now in Wiltshire. The first few years annual meetings were at our house, now tend to be zoom, and we skip some years as no real change.
Questions to ask are which platforms do they use to invest, are investments actively managed or just advised, fees charged, approx number of clients on their books (more specifically number per regulated advisor).
Those little stars of trust on internet are fairly useless for FCAs because people don't boast on record about making money, more likely to moan if bad so don't reflect the good ones well.