You travel to Spain. Your British IPTV works fine. Or it doesn't. Depends on the reseller's region locking policy.
Here's the access control. A British IPTV reseller can restrict streams to UK IP addresses only (region lock) or allow worldwide access. Region locking prevents international use but may satisfy content providers.
What actually works for travelers is resellers who allow worldwide access. If you travel frequently, region-locked resellers will leave you without service abroad.
I traveled to France for 2 weeks. My British IPTV reseller had no region lock. Worked perfectly. My friend's reseller was UK-only. He had no service for 2 weeks. Guess who switched resellers after returning?
The pattern that keeps showing up is that IPTV reseller UK operators who serve expats and travelers explicitly allow worldwide access. Those focused only on domestic UK customers may region-lock.
Honestly, if you travel, ask before buying: "Does your service work outside the UK?" A IPTV reseller UK answering "yes, worldwide" is what you need. "UK only" means no service abroad.
That said, some resellers allow worldwide access but warn about performance. Distance increases latency. That's acceptable.
In most cases, British IPTV resellers without region lock are essential for travelers and expats.