Hi
Around 2007'ish I helped my best friend and his wife move back from Amsterdam. I simply hired a Luton sized van - these are the ones a bit bigger than a transit and have the electric flat big tail lift at the back, drove it over there, filled it up and drove it back. In terms of the actual process that's all really there is to it. In terms of the legalities etc, I'm unsure as he'd done all of what/if is required previously. As it's within the EU, I don't think the items will be taxed. Perhaps ask around and look at the immigration places etc, you might have to fill in forms to declare the items are 2nd hand etc, but again im not sure on the situation if they've just been given to you. I'd 'guess' that it shouldn't be an issue, after all, if you purchase something on ebay and it's in Holland, you can indeed just drive over, pick it up and bring it back (generally) so I'd expect 2nd hand furniture to be the same.
Keep in mind that the hire costs, fuel and channel crossing costs will add up. I doubt you'll want to do it all in a day, so preferably over a weekend so you can meetup with your friends too. So do factor in the costs of that aspect as well. You 'might' find it's better for them to give away / donate / sell their stuff and for you to purchase your furniture here etc etc.
Cheers, DtM! West London & Slough UK!