green granite
Aah.. sorry, misread your post. I assumed you wanted were thinking of plugging an extension strip type assembly into the C13 sockets. Apologies.
That sort of thing should only be done with the C19 sockets present on the larger units.
But yes, single cables are fine as long as they feed a single device.
Booglebox
swears by the APC "Smart-UPS" line.
Agreed, although if budget permits, I recommend "Smart-UPS Online" rather than the plain "Smart-UPS". The "Online" variant are double conversion with true mains isolation, therefore giving you zero switchover delay during powerloss becasue all that happens is that the rectifier drops out of a circuit that was already live (i.e. mains power is always the secondary power source).
But both types have given me many years of faultless service.