Are "Debtor tracing services" in the UK legit? Has anyone ever used one?

I don't want to get into specific details, but my (former) friend owes me a significant amount of money and has disappeared. He'd been sending me an email about once a month with excuses about why he hadn't paid me and why he'd been so hard to contact, constantly saying he'd get a job and start paying me back. The last email I got from him, he said he was homeless and had no one left to turn to, but that he'd keep checking his emails. That was 7 months ago and he hasn't responded to any emails I've sent him since. I want to sue his ass and get my money back, but I'm worried it'll be impossible to serve him if he is actually homeless. Apparently there are "debtor tracing services" companies in the UK that will find the most recent address, and other details, of people you're looking for. The company I found offers a basic address finding service for £35. I figured it'll be worth it to find out if he's telling the truth about being homeless, and allow me to serve him with the court case if I need to. I have an email from the end of 2023 where I say "Hi [name], as of [date], you owe me [amount]." With him replying saying, "I can confirm that as of [date], this is correct." So, if it goes to court, I have solid evidence that he owes me the money. Are these services legitimate and worthwhile? Does anyone have any experience with them? I feel like a complete idiot lending him so much money. I'm still considering whether to take him to court, but I want to know if this is a worthwhile option to pursue.