Ronan,
The OXO and the worcestershire sauce i have purchased at the bigger supermarkets in China. I don't think there is any herb or spice that you can't find in the spice markets, they will have it somewhere, but maybe in smaller quantities, that's not quite as noticeable as there main fair. The OXO can be a problem at times, i think they buy it as job lots and you have to wait till the next job lot comes up. But they do have all the things that you mentioned in the bigger supermarkets, you may have to hunt around a bit.....
I used to cook a lot of Italian dishes, and never really had that much trouble locating the ingredients. OK, i admit i did have help in locating some of the things i needed at times, but then you do have Sunny and Yamaha to help you!!!... lol!!! When you really look around in China, you'll find there isn't that much that you can't get....
Wouldn't hurt to take a small box of the OXO cubes with you, they aren't going to break/spill all over your suitcase either!!!... You know , ...Murphy's law and all that!!! ...hahaha!!
David......