Mozilla Firefox Search Bar
Firefox has a search box, just next to the address bar which allows you to select which site you wish to search, such as Google, Amazon, etc.
A lot are available at mycroft.mozdev.org/download.html, however, they are often affiliated or don't have a great selection of UK ones:So here are some non-affiliated search engine addons for UK Firefox users, simply click on the name of the site to install them:
MoneySavingExpert Bargain Forums search