Tesco is the biggest supermarket to stock Israeli produce, which includes Carmel fruit and vegetables, and products labelled as produced in the "West Bank".
However, it seems that UK consumers are showing an increased interest in buying Palestinian products to show their solidarity with the people of Gaza. In particular, some Asian grocers around the Manchester area have noticed increased sales of fairly traded Palestinian olive oil, when they stock it.
For anyone who wants to show solidarity in this way, News From Nowhere bookshop on Bold Street has Palestinian soaps and crafts on sale. Companies that import Palestinian fair trade products are Zaytoun and the Olive Cooperative. You can check the availability of their products, (including but not limited to olive oil) via http://www.zaytoun.org/, Zaytoun CC, 33 Carronade Court, Eden Grove, London N7 8EP, and
http://www.olivecoop.com/, Olive Cooperative, Bridge 5 Mill, 22a Beswick Street, Manchester M4 7HR. 0161 273 1970.