I'll ask before others, but where are you in the UK?
suggestions will be different for south coast of Cornwall than for north-east coast of Scotland.

I live in Birmingham, West midlands. Thanks for taking the time to help.

There's a pretty small flowered Clematis cartmanii 'joe' - if you can keep the roots cool.
A small variegated yucca "Golden Sword" - I looked at this for my soon-to-be front garden but ruled it out as it needs full sun (which I won't have)
Holly-leaved Osmnathus Goshiki - leaves go through lots of colour changes through the year, plus scented flowers, plus berries. I saw this recently at Jacksons nursery in the Potteries (one of my top three nurseries) so shouldn't be a problem in B'ham.

If you want something with bright flowers, azaleas or rhododendrons (though someone might know better whether you need a bigger pot for these)

Thank you so much