My name is ***** ***** I would be happy to help with your celadon bowl.
This is a very decorative bowl in the Chinese porcelain tradition, a relief design carved into the leather-hard clay, coated in celadon glaze and fired. So yes! It is celadon in style, but not that old, and we can tell that from the mark on the base.
It's a four character phrase that reads (top left, bottom left, top right, bottom right):
which translates as "Longquan China".
"Zhongguo" or "Middle Kingdom Country" to give it its literal meaning is how the leadership in China in the modern era wish the name of their country to be styled and a usage that was generally adopted post-1970s.
The "Longquan" refers to the celadon style of glaze made famous at the Longquan kilns in Zhejiang province of South-Eastern China and which this bowl is emulating. So this is a newer mark, probably post-1990.
Unfortunately this era of Chinese porcelain isn't old enough yet to have generated much of a premium with collectors so its value is purely decorative. As such, and given the small chip on the rim, I would say that £10 is a fair retail price for it.
I do hope this is not too disappointing, however, I'm sure you'll understand that whatever its value, you will always have a beautiful bowl made of top quality porcelain.
In future, if you are looking to tell old from knew, the best way is carefully to examine the high points of the glaze and the rim and look for very slight wear that indicates age. Also, look for seals on the base that are hand painted rather than stamped (this one is stamped). To tell a stamped mark from a written one, a stamped mark often has little gaps where the stamp bridges. A hand painted one has strokes that have both light and dark colour in them where the paint thins and thickens, whereas the printed ones are an even tone.
These are just a couple of things to look for to begin with. There are many others that you'll come to recognize the more you study the real thing in pictures and in museums, an endless source of fascination and interest, in my opinion.
I do hope this helps!
Please let me know if you'd like me to explain or expand on any of the above, I would be glad to.