What to put smart pots on? (Indoor tent) Advice for noob appreciated...

Alright people, new grower here. First off I'd like to thank everyone on this forum for helping me gather lots of useful information for my first grow, which I am going to attempt very soon.

I'll be growing 7-9 plants under a 600w hps and 300w led combo in homemade organic soil mix/smart pots.

I am wondering what I should put underneath my smart pots to help with drainage?

I seem to be finding conflicting information - some people say they are fine just on the floor soaking the water back up, some people say you should get rid of excess water to help them dry out a bit before watering again. I'm inclined to think the latter is true, but may be wrong.
I was thinking of setting up something like this:

https://www.rollitup.org/grow-room-design-setup/378720-diy-drip-tray-soil-grows.html

Is this a good idea?
Would metal sheeting definitely be ok? I have heard that it can act as a radiator for heat. I have and electric tube heater to use in my grow tent (with thermostat to help control heat, my 600w is air cooled and I live in a cold area) which I was planning on putting somewhere in the bottom of my grow room as heat rises... However I feel if I do this with the smart pots on the metal sheeting, then the heat could radiate off the sheeting and make the plants too hot? Will this even matter though if the heater is set at the correct temperature?

The other corrugated roofing I can find where I live is made of pvc which I have heard is bad to put in a grow room?

Thats the method I was planning on doing anyway as it looks pretty effective, and ideally I would like to be able to water my plants and dispose of the excess water later. It would be nice if someone could chime in on whether I will be OK with the metal sheeting or whether there are other good alternatives.

What do all you indoor smart pot users do?

Any other advice you can give to someone attempting their first grow would be appreciated also.

I'm looking forward to the learning process, but I want to do everything as well as I can and hopefully get a good first grow too.
I've got some nice seeds and if all goes to plan I may post the results here later..

Thanks!

I grow in Colorado, so the humidity thing may or not be needed where you are, def is here.
I use Botanicare trays, they have channels for the excess water to sit in and not have the plant sitting in the water. This allows the excess water to sit in the room and add much needed humidity.
I would not use sheet metal as even hot dipped galvanized will eventually rust if kept submerged long enough. PVC is perfectly fine in a grow room, hell many systems are based on pvc and abs plastics. My Botanicare trays are white abs i believe, but i still would have bought them if they were pvc.

Hi, thanks for the info.

I can't find the botinicare trays you use where I am, I'm in the uk. They sound good though. Think I'm still going to stick with that design I was looking at, it should do what I want. Good point with rusting, I thought that might happen with sheet metal, the supplier I was looking at claimed to use a thin coating to prevent rust though. I have found an alternative corrugated plastic sheet to pvc - 'bitumen' which is supposedly non toxic, environmentally friendly and good for agricultural use. Think I may give that a try.

I know I'm probably being overly paranoid with the pvc thing, I have read a few articles on it and wasn't entirely convinced but I don't like the sound of what happen to the plants in a poster on this thread:

https://www.icmag.com/ic/showthread.php?t=103953

And would rather avoid something like that happening to my plants. I'm sure pvc would be fine and thanks for the advice but I'm probably going to try the alternative and see how that works out.

I'm anxious to get growing! As I said you may hear back from me if I manage to grow some nice buds. I'm optimistic but its my first grow so who knows what I'll end up with..

Thanks for your help.