It's a Buddleia globosa, or one of its hybrids - Oh! I've just seen that your question comes from that page, so you know that already.

You could collect seed - Buddleias grow quickly so you'd soon have a decent sized plant.
If you want to take cuttings, pull off some shoots about 3-5 inches long, so that they bring a little "tail" of bark off the parent branch with them (that's the "heel" that you were told they'd need).

Strip the lower leaves off the cuttings and remove any flower buds, if there are any, and pop the cuttings into a pot of compost, sliding them in round the edge of the pot. There shouldn't be any leaves below the surface of the compost. Put a clear plastic bag (like a sandwich bag, for instance) over the top half of the pot and the cuttings, and hold it in place with a rubber band round the pot. Blow the bag up so that the bag doesn't touch the leaves if possible. Put the pot with the bag on its head on a saucer in a light but not sunny windowsill and hope for the best.

You'll know if any cuttings have taken as they'll start making new leaves and roots will appear at the bottom of the pot. When/if that happens, you can take the bag off, leave for a few days to get used to the open air, then pot up any rooted cuttings separately in smallish (3inch or so) pots. You'll be able to plant them out when they've got a good root system going.

hi Beattie!
Thank you so much for the advice, i've potted up the cuttings now but didn't know about the plastic bag bit so thanks a bunch, i'll get that done today!
I'll up date the pic's if they take aswell, fingers crossed. xx