I'd wait until spring but really it depends where you live in the UK. The Osteospermum are not fully hardy and can need protection in winter.

It depends on where you are in the UK as to the hardiness of Osteospermum jucundum. Mine are fully hardy in Somerset. However, any other Osteos aren't, despite what Garden Centres say.

I'd leave it until the spring, too, however, because they need to get their roots established before the cold weather comes, and the Geraniums will be vanishing soon anyway.

Many thanks to you both for your advice, much appreciated. I had thought that if I planted now it would give time for the Osteos to get a hold before the winter, and would avoid the need for any serious watering in the spring (the bed is for my elderly father in law who is not very mobile). I know there will be no real growth or flowers till next year and jucundum seems to be hardy in my garden so I thought it might be all right, but will now think again.

Thanks again for your advice.