Brilliant link Irvine
This a great start for you Jay, i would take what irvine says and add, look at Baetis Niger (iron blue), heptagenia sulphurea (yellow mays) and the Ephemerella ignita (BWO).
This covers you for most of therest of hatches on the Don, although there is a good head of Caenis too.
And Baetis scambus (small dk olives) which can come of all year.
matching the hatch is fun, but most of the bugs can be imitated by a handful of flies in different sizes, finding out what they are , is what it's all about
Sandy