OK… I screwed up… and wiped/reloaded my urbackup server - upgrading the physical box from 2012R2 to 2016 (it was mainly a HyperV server, with extra disks)
So the main volume with the urbackup folder, and 40+ clients’ backups is still intact… D:\Backup
…but I forgot to backup the main database beforehand!!! 
So… if I reinstall urbackup… and point it to the same storage folder: D:\Backup… and if I get the clients reconnected to this Server (will have same name/IP address) - I’m gathering it might need a new ‘key’ on the client?
Will the clients (who haven’t changed their name), ‘pick up’ the existing backups, that have been running for the last 2-3 months?
Will they start storing a new instance of data?
or is it best to just start from scratch? - Not overly fussed if I have to… some clients had a lot of data, and it took a couple of days over wifi for their initial backup… that’s all…