Converting old greenhouse to grow room-advice needed

I've got an old 12x12 fibre glass greenhouse (with power) sitting on gravel and I want to take advantage of this opportunity. But I'm unsure about the gravel, leaks and what would be the best and most cost-effective way to do this. It will be a first time grow so all suggestions are appreciated.

Cement the floor with a slope and include a drain in the center is the best dream for green house growers ...lol

along with good safe power sockets

and Green house placement ...off course ..lol

good luck

Concrete floor with a floor drain for sure, they make those really awesome channel drains to put in the floor. I also like epoxy floor coating, no speckles so you can see anything that doesn't belong.

https://www.amazon.com/Drainage-Trench-Channel-Plastic-Length/dp/B07FLP29SY/ref=asc_df_B07FLP29SY/?tag=hyprod-20&linkCode=df0&hvadid=309738825993&hvpos=1o5&hvnetw=g&hvrand=1823582926483251290&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029117&hvtargid=aud-801381245258:pla-570161207185&psc=1&tag=&ref=&adgrpid=63356877524&hvpone=&hvptwo=&hvadid=309738825993&hvpos=1o5&hvnetw=g&hvrand=1823582926483251290&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029117&hvtargid=aud-801381245258:pla-570161207185