Both lures will take fish throughout the year - personally I never do particularly well with damsels, probably because I don't fish them very well

A cats is always my go to lure but if a stockie is in a mood to take a lure I reckon it will take anything it hasn't seen too often.
The best bet of course, is to ask at the lodge and ask other fishermen.
What line to use depends on several factors. Personally, unless the fishery is deep and the fish are lying deep and you need to get the fly down to them fast, I'd stick with a floating line and a weighted lure on a longish leader if you need to go deep - and an unweighted lure if the fish are feeding high in the water. (This is for pulling a lure)
If you want to fish nymphs, you could use your inter line with a washing line setup and a slowish retrieve (look up washing line). Depending on how they want them, you could also try them static on a floating line.
Keep trying different depths, different retrieves and keep moving round until you get some offers.
If you've the time, nip into John Norris in Penrith and have a chat with the lads there - one of them will know your fishery.
Tight lines and let us know how you get on