I need 36" grow light setup

[Rockporter]

I finally have my insulated and wired 8 x 10 shed here, my husband built the inside for me a couple of years ago. It has it's own breaker panel with 20 amps total. Two 10 amp sides. I have a small A/C with a fan that runs continously when the cooling shuts off, this keeps the air moving in the shed. This used to be my crafting shop but since we moved to a house I thought I would change it's use to the garden. Maybe if I am successful I will sell some seedlings at the farmer's market.

I need to setup some grow lights but really can only fit 36" long on each side(2 sides) of the bench due to the inside frame in the middle of the bench. The bench is 24" deep so I can do alot with the space provided here.

I see the recomendation to have at least 20000 lumens total and am having a difficult time finding a 36" long fixture as well as knowing how wide it is. I would like to use T6 if possible because it can be used in a T8 setup without having to spend the money on the T5 but it has the same lighting as the T5 does and they come in 36" length.

See them here
http://www.naturallighting.com/cart/store.php?crn=591

So, can anyone help me figure out what fixture to buy and how many bulbs it needs to provide the 20000 lumens needed? And are those lumens available in total for 36" setup?

Thank you in advance for your knowledge, I have found this forum to be a nonstop learning curve.

I will add photos of my shed later.