Hi Kim, you ask about the temp "recommended".
Yes, that temp. would be "COMFORT"i.e you (the average female)would be wearing good thermals,beanie and socks. In most cases women sleep colder than men.
"LIMIT" is the place you could push it (but should really avoid) with
more than thermals i.e. pants over thermals and down jacket over thermal top and thick beanie and thick socks/down booties for example, but really you would only look to do this if you are
experienced and well prepared. I would say go for a higher than normal R value, if you are too hot you can always undo/put a leg out --R3-5+. Personally I would go for 5+ for the first time purchase. Sea to summit comfort maybe (the red one and not the lightest but very comfortable) Snowys have the best price often and might be a good place to start, it has two layers-so if one punctures you still have air in the mat.
Please check this review for the bag Zapruda mentioned.
https://sectionhiker.com/western-mounta ... ag-review/ This bloke knows his stuff and backs up Zapruda's recommendation. Pricey perhaps, but sounds brilliant.
I would definitely not go to a quilt until you have used a bag in anger. They are not for everybody, at least at first!
And it is cold weather that can really highlight problems-anything is OK when it is mild.
You can't be cold whatever happens (!!) as it can lead to risks/problems and so many factors are at play here as one poster said. Gender,fatigue,metabolism,state of fitness/wellness all play a role. It is always better to be a bit warm and be able to wear less than be trying to find more and more clothes during the night when you continue to wake up shivering. We have probably all done it and learned from it!
Get a few nights like this and it is very draining/problematic. I know the One Planet bags (Melbourne)can be quite heavy BUT they are renowned as being "true" to the stated ratings for "Comfort".
Also do some more research on "EN ratings for sleeping bags"-forewarned is forearmed. All the best.It will work out.
PS You ask if a comfort rating of 0C is enough? If you want to ensure a true comfort rating not all bags are equal-The bag above is.-but I would go 5C past that and look for about -5C so if you sleep cold as you said you would be still covered at 0C.