Building regs for stud walls

My house has a stud wall that supports the ceiling joists and part of the roof using struts, as well as now it carries the weight of stored items in my loft. So yes one must check first in the loft to see what is being supported above any wall, stud or not, and some brick walls can just be non-load bearing walls too. All depends on who drank how much before drawing plans and approving them and to the person who carried out the job. I don't drink except on special occasions. Freddy is always nearly intoxicated.

to the OP, if the walls are non-loadbearing, then your answer would be yes and the details you would give would be moved non loadbearing stud wall from position A to position B on DD/MM/YYYY, and as your thinking about it how about take some pictures to back up the fact that the works aren't notifiable assuming there aren't any other reasons they might be as Tony commented.
I'm ****ed as a fart

Yes, your building works should be declared on the sellers form, and they should also be reported to building control, not because moving an internal stud wall is necessarily notifiable, but because you're forming an additional ensuite, and alterations to sanitary drainage are always notifiable. You also have obligations under parts E, F and P and possibly B, C and M if not more, depending on the scope of your plan