Yeah, you can either bring it back yourself (it's all flatpack, so you could fit a fair bit in a car or on a roofrack) or get it delivered. The delivery is actually Stg£100 for two pallets, and two trolleys can be more than two pallets (not quite sure how they work it out, they are nearly the same but not quite).
I actually did it both ways on two different trips, and TBH it was so worth paying for it to be delivered because loading and unloading it ourselves was a nightmare - that's why the second time we went for delivery. It actually worked out about the same as hiring the van, but you do need to accept the fact that it's very difficult (if not impossible) to estimate in advance how many pallets you'll end up with, so you need to be prepared to be shocked at what it's actually going to cost you.
I think it's more worth it with a lot of stuff, because if you only have say one pallet you still have to pay for two (because that's the minimum). If you were going to just get a wardrobe I don't think it would be worth it, you could definitely fit it on a roofrack, or possibly in the back of a large car with the seats folded down. The website does give the dimensions of the flatpack boxes for each item, if you feel like adding it all up.