Hi and welcome here, Samantha

It’s a complex area - see for example:

www.thirdsector.co.uk/.../1132747

Simply paying eg an hourly rate without separately identifying and paying under the separate category of holiday pay the appropriate statutory minimimum or higher percentage is I think indeed unlawful, but if you don’t actually lump it into the hourly rate of pay, then it can probably be argued that it isn’t ‘rolled up’ at all.
Ideally, the holiday pay element I suppose should be ‘banked’ by the employer of casual workers and the like and paid to them whenever they elect to receive it so long as it relates to a period they’re not actually doing paid work. Then technically / nominally the employer is paying holiday pay concurrently with actual holiday taken.

But to introduce such a system could be administratively complicated and is just a bit of a charade leading to exactly the same thing, so why bother, perhaps?

Your employer’s choice I suppose, but if they pay at least NLW plus an uplift separately identified as holiday pay of at least statutory holiday pay percentage I’d say that the chances of it ever being challenged were minuscule and even if it were challenged and found to be contrary to ECJ Law, what detriment has the employee suffered by paying them this way? - arguably of course, none at all.

So, I think the solicitor who told you this wasn’t knowing or telling you the full story.

In reply to David:

Very Helpful!
Thank you very much for this David.

Sam

My approach at my last job, where we had a lot of zero-hours workers, was to pay the holiday pay as a separate element *and* to give ZHWs the contractual right to ask for paid holiday instead of the holiday pay element.

No one ever asks for less money.