There is a huge two-volume collection published by Dover, and inexpensive, called The Fitzwilliam Virginal Collection. This and a few others like it are the source for most or all of Byrd’s keyboard music and the others of his period.
They are perfectly legible, but in older English-style engraving from the late 19th century or early 20th century. A little small but you can read and play from them.