1. https://www.currensea.com/

This enables a UK based person to buy in non-GBP with low fx fees

2.
https://azte.co/buy/online-stores?country=GBR

This enables purchase of Bitcoin

3.

https://bluewallet.io/

This enables receiving the satoshis bought under 2. before onward transfer to the freelancer

There’s probably a better solution but this is fairly non-technical albeit expensive.