routes from Stafford and Penkridge.
From Stafford, I’d say Millenium Way to Newport, then via Church Aston, Lilleshall & Preston on Weald Moors to the north end of the Silkin Way near Shawbirch. If your nav is up to following the twists and turns of the bastardised route that now takes through Telford, it’ll drop you perfectly down to Coalport.
From Penkridge, either head NW to join the Millenium Way at Gnosall, or (probably shorter) go basically west via Wheaton Aston, Gt Chatwell, south of Lilleshall and then cycleways from Muxton westwards to join the above Silkin Way.
Easy peasy!
Either of the above, followed by a ride down to Bridgo, makes for a longish day.
Oh, and I’m pretty sure the route along the Severn valley is no longer gravel; think it was surfaced a few years ago.