Look, I'm not going to sugarcoat this: Winning London is a relic from the peak Olsen twins direct-to-video empire, and it shows. Yes, it's safe. Yes, it's wholesome in that bland, inoffensive way. But it's also mind-numbingly formulaic and dated in a way that makes it nearly unwatchable for modern kids.
The Model UN premise could have been interesting, but it's just an excuse to put the twins in London for shopping montages and innocent flirting with British boys. The ratings tell the story: 5.4 on IMDb, 2.9 on Letterboxd - even nostalgia can't save this one.
If your kid is genuinely interested, fine, it won't hurt them. But there are approximately 10,000 better ways to spend 90 minutes. Even for a sick day movie, you can do better. This is the kind of thing that gets turned on, ignored, and forgotten about while your kid plays on their tablet instead.