So for folks that live in the UK, and for people who didn't know this yet, you can get free 3mobile(probably other operators too) SIM cards online and use it for validating your IG,TW,FB accounts. If you go into the store, they tell you that you need to top up with 5pounds but in fact you dont. Just order it online and get it in your mail put it in your phone, wait for activation message and its done.
The other thing is that you can order several cards without issues and keep doing this over and over.
Most likely everyone knew this(as always turns out to be) but still just decided to share!