I've always found adultwork to be almost completely useless as a male escort for getting clients. It's ok for selling video clips if you promote the clips elsewhere and just treat AW as a very expensive, very ugly, horrible to navigate, 1990s looking video hosting site run by people who will take every opportunity to be difficult.
Sleepyboy, hunqz and rentmen are the main directories for male escorts in UK.
But, I recommend that he think twice about trusting any directories with his identity.
My only regret from the 14 years I've been a full time provider is that I gave my ID documents, selfies for verification, debit card details etc to directories.
I don't use directory ads any more. I get enough genuine clients from regulars, duos and from my own personal website.
I wish I'd never given anything connected to my real name to any directories. My advice would be don't use directories at all if you can avoid it. Better just to make your own site to begin with and work on SEO to get a search ranking where clients find your site in search engines.
If you must use directories, give them fake selfies which you can easily crowdsource someone to make for you, fake ID which is easy enough to get from the dark web, and pay by crypto.
Eros, backpage, Craigslist, rentboy, Ashley maddison etc have all either been busted by the feds or hacked.
Directories don't bother to delete your verification documents after verifying you. They don't even encrypt the files. They're too lazy and incompetent to be trusted with your identity.
Servers have been hacked or seized in the past and it will happen again.
Think of what facial recognition and reverse image search tech is like now and what it might be like in another 5 or 10 years before doing anything that connects your face and real identity to your work persona.
Tryst is the only directory I know of that claims that they delete verification documents after verifying you but it's more popular in USA. He won't get any clients advertising as a male escort on tryst in UK unfortunately. It is the only directory run by sex workers for sex workers. I'd love to see many of the other directories, especially adultwork and eros, get shut down and for tryst to become the go to directory for UK.
I've written a guide for getting started as a male escort which I'm happy to send you if you message me here and if he reads that first and still has questions, your friend is welcome to contact me.