@Kamila33 The thicker sheets will take up more space in the washing machine, maybe something to consider. I couldn't tell you where to get them, though.
I'm not a sheet ironer- I line dry and find that if I take them out of the washer right away when they're done, shake them out good and hang them, they dry pretty smooth. If I leave them wadded up in there for awhile before hanging, they do sometimes end up quite wrinkled.
I've found that if you need to iron them, it's way easier to do it on the bed- put the bottom sheet on, when it stretches, most of the wrinkles come out and you can just run the iron quickly over. The top sheet I'll lay out folded in half on the bed, iron it, pull the rest up and iron that, and then flip it out and finish making the bed. I don't do a stellar job and don't care to. None of my guests has complained about the bedding.
I even have a couple sheets I patched when they got a small hole and I didn't have time to go shopping for new ones- I thought guests might find that weird, but one guest actually commented on how cute she thought the patches were.