It turns out my issue was down to communication form the AdminStudio client to the WFM Web server.
The Client could see the SQL box fine and hence do all the standard App Catalog / App Manager stuff, but the AES connection was to the servername only e.g. http://wfmserver
Strangely when I log in it didn't say anything about that server not being accessible, yet when I complete the workflow it doesn't roll it on in WFM, although the system did seem quite slow.
However the AdminStuio log said explicitly that it could not find the WFM/AES server and that it could not therefore update the WFM sompletion status (great!).
On reviewing the Enterprise server tab I could see the server connection to WFM was not available but from a separate browser it was fine (even when checked my Proxy).
So I tried the FQDN of the server in the connection and suddenly DNS responded, the thing worked fine hence:
http://wfmserver became -> http://wfmserver.subdomain.domain.com
Then my response times came back (since it wasn't timing out the search for the server) and I'm happy again.