Thanks all for some really good suggestions.
Pieris do look good, but are better with some slight shade,
Camellias too big and spready of habit, Cordyline are a possibility.Cistus are great in full sun, we have lots in the garden, but not good in pots as they can freeze over the Winter.Leucothoe are nice, and there are several varieties, all with colourful leaves, so another possibility thanks.
Nandina Domestica ( Heavenly bamboo) is another possible choice as we have one growing in full sun and it is very
hardy, and colourful.
Will have to get to the garden centre soon and have a look.?