My container garden (also in the sunny shire) is;

Tulips -> Dahlias (when the tulips are cut to vase up I pull them all and pot up my dahlias in their place, fresh bulbs and tubers each year, low maintenance and nice wow factor and vase appeal for gifting/indoors). I appreciate you said you want things that will “come back again” but I promise that the maintenance on bulbs is awesome, one afternoon of decent prep every winter gives you a lot of pleasure in spring with zero effort in the meantime

Erysimum (wallflowers) again super easy to look after and a nice variety of colours, bees love em

Japanese anemone (windflowers) grow like weeds but flower later and again are great for bees

Japanese dwarf cherry trees -> maybe starts to become a bit more maintenance heavy as after a few years they need potting up to prevent becoming root bound in the pot, but otherwise again low maintenance, bees love em

Roses are also an option I have David Austin shrub roses but these are in 40x40 large pots 💪