Hi everybody,
Just a quick update to let you know that I sent the address request change on October 2018, on March 2019 I took the test and told the officer that I requested the change of the address to Spain but that it wasn't changed on ECAS. She wasn't very surprised. Well, I received an email yesterday about my application and I have my oath ceremony in 1 month. So there hasn't been any issue with moving abroad. I still got my citizenship and didn't have to fill the RQ.
So, as long as you do everything right and don't lie, there shouldn't be any issues.
Thanks again for your help!