The Fifth Doctor Box Set: Psychodrome by Jonathan Morris, Iterations of I by John Dorney
This is a set of two Big Finish plays released in 2014, featuring the full early Fifth Doctor line-up - Peter Davison, Sara Sutton, Janet Fielding and for the first time Matthew Waterhouse.
The first story, Psychodrome by Jonathan Morris, is explicitly set immediately after Castrovalva, and features a complex narrative of the Tardis crew dealing with their own images of each other. The guest cast are put through their paces, each of them having to play three different roles - particularly Robert Whitelock, who does three different Doctor-substitutes as perceived by the others. As Peter Davison points out in the extras, it's good to have a bridging narrative from the uneasy relationships at the end of Castrovalva to the relative comfort of later stories.
I spotted Iterations of I in my St Patrick's Day post of Doctor Who stories set in Ireland, of which the vast majority are Big Finish audios. It's set between Black Orchid and Earthshock, Adric in his hubris attempting to pilot the Tardis and ending up on an island off the Irish coast where the crew become involved with a missing person investigation, a strange cult and the awful prospect of sentient numbers, a gonzo concept which is well-used by not being too deeply explored. The wonderful Sinead Keenan is the lead female guest, sadly not depicted on the cover. There's no particular reason for this story to be set in Ireland, but there's no reason why not either.
You can get them both here.