UK Freelancer temp work in Spain UK contracts tax advice

Hi, I wanted some tax advice as I’m moving to Spain for 6 months and am currently a sole trader in the UK, working as a freelancer for various UK registered companies. My plan when I am in Spain is to continue freelancing for the UK companies in freelance contracts with them invoicing in GBP and earning the GBP into my UK bank account. The projects I’m working on mean I can work remotely in Spain and then travel back to the UK for certain live elements of the projects. This isn’t a permanent move and I plan to return to the UK after 6 months. In this circumstance can I stay as tax registered in the UK and not register in Spain and then process my UK self assessment as normal? Or do I need to register in Spain and then only pay tax in Spain on those earnings?

also if I was to pick up freelance contracts in Spain as well as continue my UK contracts, earning money in both GBP and EUROS what are the tax implications for this? I’m just conscious I want to make sure I’m paying tax in the right place but not double paying or losing out on income.
Thanks in advance!