Do you want a job out of it?
That is all.
I also assume that you intend to pirate Photoshop, since it is £650 and the choice between £0 and £650 doesn’t seem to be anything other than obvious.
That’s your choice, but if you go ahead and pirate Photoshop and learn that, then be prepared to be tied to a product you don’t own and will forever battle with. It is never, ever worth it to go down the rabbit hole of having to pirate software because you are ignorant of the alternatives. It limits your choice of platforms, limits your range of your skill set and if you ever go into business, you’ve then tied yourself to spending £1800 a year on upgrades. Have fun.