I like my Logitech mouse a lot! It's a wireless mouse with a little USB stick to plug in.
Sometimes they come with cool art on them! (Mine has the owl pattern
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It's been fairly reliable so far. My clicking is pretty accurate after adjusting the motion sensitivity and it's got a good lifespan for the price. I know they make fancy mouses for gaming, but all I personally need is the three button mouse style. Logitech has several different sizes of mouses as well. The one I linked in particular is on the small side, which happens to fit my hand well.
Not sure if they're available in the UK. In the US you can find them at the ubiquitous Target.