If you’re building for tourism then you may well need to aqaint yourself with ………
General Building Regs
Asturias Laws concerning operating accomodation
On top of the above, you will find that your local village/town council can enforce some items e.g. number of parking spaces, and if you’re messing around with trees or in a wooded area, you may well also need permission from the equivalent of the forrestry commision as part of your license to build.
It is increasing difficult if not impossible to do a DIY build without involving (and paying) a number of licensed qualified professionals. E.g. electrician.
There is also a requirement for installing solar energy in your proposal – again, payment is required for a licensed professional to submit the project as part of the planning process and you won’t get the build signed off until they’ve tested and certified the installation.