Good morning, Bernie.
I've recently been bed and sheet shopping in Fethiye and found all the beds in metric sizes. It helps to know what dimensions you prefer in metric sizes, rather than in Twin/Queen/King, etc.
I wanted large single beds that can be combined into a extra large bed, so passed on the "normal" single sizes (80x180, 90x180) and went for 100x200 (large single or Twin XL), which when combined made 200x200 (Emperor). I easily found high TC cotton sheets at English Home in Erasta, but could have purchased poly/cotton blends almost anywhere.
You can also find standard doubles 140w, Queens 150w, Kings 180w or Super King/Emperor at 200w.
I think a lot of the confusion comes from the American bed sizes, whose dimensions are in inches and feet that don't really match up to the metric sizes we see everywhere else (Twin=3ft, XLTwin=3.5ft, Double=4.5ft, Queen=5ft, King=6ft, SuperKing/Emperor=6ft8in). In the UK, we often have sheets that are made for US-sized beds, which don't correspond to metric equivalents.
Hope this helps!
Dale