My band is going to play Fairies Wear Boots at a school thing and i didn't know whether or not to have some kind of preconcieved solo made for it or just improvise. Also if this is the wrong forum just let me know where to put it.
If you have confidence in yourself, go for it. If not, you might want to write some stuff out to help you get through it.
figure out a few "themes" or ideas in yout solo, sorta like the basis of rifs but change them and move to and away from them in you solo
Study the patterns that Tony Iommi plays during the studio recorded solo if you want to have the same style as him. If you can improvise decently in the blues scale then I suggest you do so. Iommi has stated that he never plays the same solo live and just improvises becase he doesn't remember the solos he recorded note per note.