C'est presque le weekend/la fin de semaine, j'ai hâte de faire la grasse matinée/dormir plus tard demain, particulièremensurtout maintenant que l'électricité est rentrévenue chez moi.

"la fin de semaine" is an ambigous word, as it can mean the end of working days or "Saturday/Sunday". The specific word that always mean "Saturday/Sunday" is the anglicism "weekend"

faire la grasse matinée = sleep until late, sleep later than usual (that would be a very idiomatic way to put it here)

"surtout" avoids having two long words like "particulièrement maintenant"

When it comes to electricity, water, etc we always say "revenir" (to come back to the spot you "left")

Pendant cette semaine entière, je'ai travaillais duranté presque douze heures par jour parce que je ne voulais pas être chez moi à cause de la chaleur.

I'd rather treat this action as a main one in your narration, with a focus on consequences/the fact is achieved, although the imparfait isn't wrong => j'ai travaillé

Je ne peuxmeurs aussi plus d'impattiendre àce de manger quelque chose de réelvrai/d'authentique ce soir, loin de la nourriture préfabriquée[industrielle ?] que je devais manger.

I can't wait to do something = je suis impatient de, j'ai hâte de
"mourir d'impatience" is even stronger, it would fit well here
"je ne peux pas attendre", however, is "I can't wait in the literal sense" (like you can't wait for something because you're expected somewhere else, for instance)

"real" in the sense of "authentic" would be "vrai"; "réel" would imply you ate virtual food

I'm not sure what you meant by "préfabriqué" (this adjective can only apply to constructions). If you're talking about industrially processed, ready-to-eat canned food etc it would be "nourriture industrielle (prête-à-servir)"