Leave Tregaron on Dolecoed Road, this takes you on the mountain road to Abergwesyn and takes in a few fords and also the Devil's Staircase. Not one for the GSXR crowd although until it hits the forests is a good UK style B road. Then the surface does deteriate a bit until after Nant Ystalwyn. Did this track at night on the Welsh National Rally and it was quite scary but the fords were only an inch or so deep even in early May.
The tourist route to Manningtree, quite a nice if short run in Essex, it starts off quite blind and tight, then it opens up with a few nice corners and good visibility. Also easily accessible from Harwich where you can take the ferry to or from Holland.