I will suggest that you go to shops or baby fair to try on the mats yourself, better even with LO. They have many designs and thickness. I got this Large size so that LO have more space on the mat to roll and crawl, even when LO learn to walk also it will be safer if LO fall(in the mat)
So many brands. I got dwinguler. They have different measurements and also thickness. And the patterns too if you want something more versatile than a plain baby mat.
Try supermom online sales. Got free delivery too. Meanwhile, tummy time on bed.
yes is good and easy to clean up too and can use it for quite long
Try Mothercare