heat mats are much better. mine is in a glass tank with a heat pad.
the bigger the better i say, just as long as u can heat it properly. dont hav the heat pads bare in the enclosure as they can burn themselfs so on the uderside of tiles or the tank if ur using towel.
sand or any sort is bad, even wood chips arnt great! anything they could eat is a big NO! geckos are susptable to impaction. use paper towel or vinyl tyles. both cheep and easy to clean and replace.
put in pleanty of places to hide as well as a moist shed box to help with shedding.
where ever u got advise from was very wrong! lol
Leopard gecko care sheet
pleanty of care sheets around and lots of knowledge available on this forum!
best of luck! xx