In Orkneyinga saga, Swein and Hakon accost two trading vessels sailing from England to Ireland. In addition to everything else, they specifically steal "English cloth" intended for sale. The text makes it clear that this is fine-quality textiles--they display it on the sides of their ship when in harbor and on their sails when, while, sailing, and name their ship after it! "Skruð", the word used there, means "cloth" most broadly (it is apparently related to modern shroud). But in medieval dialects it seems to have meant particularly good-quality cloth, particularly the quality suitable for use as liturgical vestments. /u/bloodswan should probably come verify that range of meanings, though, since I haven't done Old English/Old Norse since undergrad.

As far as time period goes: England of course is famous for its textile exports around the time the sagas appear in writing. But there is some possible evidence of cloth export in the early Middle Ages. At least, we know that insular missionaries to the continent took nicer textiles with them--there is a stash of embroidered textile that survives in Belgium, for example--and I know of at least one textual source off the top of my head that implies Anglo-Saxon-produced garments were known more widely than just among overseas monks and their continental brethren.