Diazepam question

ok well i got prescribed diazepam for my surgery, i've been taking 20-25 mgs. for 3 days straight except today... tommorow i get my surgery with novocaine. i was thinking about doubling my dose to 50 mgs. so i can be completely relaxed since i have natural tolerances to many drugs.... anways the half life of diazepam is 20-100 hours, and the day after i take the valium i'm planning on drinking.. people have told me that this could lead to over-intoxication as the valium is still in my system because of it's long half life, is this true? because it's not like i'm still gonna be feeling the effects of valium the next day but it would still be in my bloodstream.i really dont understand how this could complicate my drinking the NEXT day because its not like i would still be feeling the psychoactive effects. any replies are greatly appreciated

thank you