What to do with agapanthus now?

Just remove the spent flowering stems, and leave the rest to die back naturally. Don't know how long you've had the plant, but once its well established and big, you can dig them up in the spring and split the rhizamatomous roots and replant immediately. They're easy to raise from seed, but take 3/4 years to flower, and seedlings don't come true from hybrid plants, which is what you've got, so you don't know what you're going to get!

Thanks Bamboo, Its new (to me) this year and had one flower stem on it. I'll just leave it as it is then for this year and wait to see what happens next.
Thanks again.........Ian xx

It's good practice with many "bubous" plants to remove the flowerhead immediately after it has flowered, to stop it from producing seed.
Why you should want to do this is because it's natural instinct to produce "young", will be converted into producing more bulbs!!!
Over the years, they will multiply exceedingly well.
The misnomer of planting them in a restrcited space is exactly that.
Winter protection is always advised if temps drop below 5C in your region. Straw, bracken, even newpaper/cardboard will do.
If you really fancy some spectacular Agapanthus, look towards new varieities from New Zealand.
I have some that have bulbs with offsets larger than my computer keyboad, and chunky stems rising to 1.5-2 metres!!!
Like the foxtail lillies, keep them warm and well drained, especially over winter, and they will reward for decades to come.

Thanks Burgundy, I'll remember that for next year. :~))