Diving into the web for some answers…
OK this is for the SCA, but the author seems to know her stuff – and she points out there’s no evidence that Western European dress really differed much and there was no notion of ‘national’ styles of dress.
Hence a Welsh peasant probably looked much like an English or French one except….(taken from above link)
The Welsh seemed to have retained the use of the square cloak (‘llen’ or ‘brychan’) longer than most other peoples.
English observers note the Welsh dressed poorly in a tunic and woollen cloak. The big omission here is an over tunic, plus they frequently went bare legged..
This is almost certainly down to economics not fashion and hence we can assume an Uchelwr could afford some decent hose!
Especially as contemporary Welsh law assumes decent woollen/linen clothes, hose, tunics and shoes are normal..