New tank! aquamanta xanti 26

[Shakeable69]

Hi all!
so today my niece had a day off school as she was sick last night and couldnt go back to school for 24 hours, but was feeling ok so I took her out to Crews Hill to look at fish and tanks, and I bought a new tank! Its an aquamanta xanti26, I think they are being discontinued by maidenhead.
Its gonna be a replacement for my current tank, so im gonna add the media from the old tank to the new one and do a straight swap, hopefully it wont need cycling?
it comes with a filter box at the back with room for a heater and with an led lamp that is way brighter than the 5w cfl that my current tank uses, so it should be better for my plants, but as it doesn't have a hood I could upgrade the light after easily.
The question I have is what substrate to use, as I wouldnt want ammonia spykes, since the fish will move to the tank on day 1.
any sugestions?

 

[Shakeable69]

So I have ordered 5kg of EBI gold as reviews and posts here seem pretty good.
Once the substrate arrives I will transfer all media, plants and fish to the new tank, is there anything i should be looking for that might go wrong?
The idea is to remove plants and hardscape from old tank, scape the new one with the new substrate, then add filter media to new filter as I slowly fill the new tank with as much water as I can from the old one, transfer the fish and then to up with water as if it was a water change, the new tank is 6L larger so it would be quite a lot of new water.
Is it a good idea to run the tank with just water for a few days before all of this happens? And then discard this water?