Hi Carole, 
I didn't find anything on FindMyPast's British Armed Forces and Overseas Banns and Marriages index collection. There are a few Wisemans, and none of them were located in Germany. 
FreeBMD.org have the following marriage in Dec 1946 
Wiseman    Thomas A        Kalke    Chatham    5b   767
Ancestry has the following details. Hildemarie is a not a common name, and they lived in Northfleet, Gravesend eventually, so not too far from Chatham. Name changes - Hildemarie was born Domnick, but could have been married previously and Kalke is a German name. We knew her husband as Alan, so perhaps he is Thomas Alan. 
I've ordered the marriage certificate from the GRO to check. 
Hildemarie Kalke Dec qtr 1946
Chatham RD
Spouse    Thomas A Wiseman
Volume Number   5b
Page number   767
This is all a big mystery considering she was my Great Aunt and I actually met her.