First of all, thank you all for your inputs.

To address the Wifi point, I spend a lot of time at work where the Wifi is capped (cannot access many sites such as even youtube), therefore I always keep the Wifi setting off on my phone, given that I have unlimited mobile data anyways this has never been a problem for me.

Moreover, I appreciate that the documentation @holydarkness suggests would be very helpful. However, the only way for me to prove a negative (prove that I am not residing in the UK) would be for me to provide my latest utility bills showing that I am actually living at my place in LUX. I wouldnt have a way to gather the documentation you suggest, as I am not yet officially moving (it has been agreed with my boss but they havent kicked off the internal HR process) - I stated I already resided in the UK as I naively thought that this way I would be able to get away with withdrawing the funds without completing KYC.

On the IP issue with the UK, the reply will be the same as for the Spanish provider, but they are still to get back to me with a more detailed response (I will update here once they do). I have to stay that I brought up me travelling frequently to the UK to explain why I have a UK SIM, not to imply that I ever played while there (although I dont think there is any way for me to prove otherwise). As the same questions can be raised as to if I ever played from Spain (which I didnt).

Provided they have accepted the IP location part, I believe my strongest defence is proving that I actually live in LUX, providing the residence permit, my rental agreement and monthly bills, my Spanish ID and my employment contract if necessary - this will place me in LUX at all times.