Kirks - I assume Ireland conforms to EUOPS and thus the minimum visibility for a CTL is IN FLIGHT VIS (not RVR) and used to be 2400m for Cat C (3600 Cat D?). Also the RVR must not be less than that specified for the instrument approach used - and you need 800m RVR to complete the CTL for the landing. No cloud base specified.
That is your answer as well, Bloggs.
Aerocat - a 'visual approach' is not the same as 'circuit'. Circuits (by definition) go 'round and round' something, but you can land stright in from a visual approach (I hope.........)