What sort of soil have you got? If it's acid, you could grow a Camellia, a Crinodendron hookerianum or a Eucryphia.

I have acid soil. I think I'll probably go for the Camellia as It's one of my favourite's. Can you trim them so they look more like a tree than a shrub?
I've seen the standard Camellia tree's but they are very small! But maybe if I plant it into the ground instead of a pot it will grow to a reasonable size!?

I have seen a rhododendron grown as a standard and it was breathtaking, but they grow very slowly so it would be a long time before it was tree size. I honestly can't think of any evergreen actual trees that have noticeable flowers apart from the two already suggested ( the first one is only hardy down to -7degrees, and the best Eucryphia for Bridgend would be glutinosa as it is the most tolerant of exposure and is also the hardiest.

viburnum tinus is evergreen and flowers

As you want a 'small' tree you could use a large Rhododendron and trim off the lower branches to make it look like a tree. It might take a while to grow or be expensive!

Thanks for all your suggestions. Some good ideas. I have a few small Rhododendron shrubs, maybe I'll try to prune one of them and see what happens.
I hadn't heard of Eucryphia or the Viburnum Tinus before as I'm a bit of a novice. I've looked both up and like the look of both of them. Both have stunning flowers. While one flowers late summer- autumn, the other flowers in winter! So maybe I'll get both but keep them in large containers so my garden doesn't get to overcrowded....and I'd get best of both worlds then two evergreen trees that both flower at different times of the year! :-)

Eucryphia is beloved by the bees! The whole tree positively buzzes when in flower!