As far as I know there are no hire companies in the north that will let you take a car south.

If you look at postings on other BBs and the local papers, you'll see that there is a great deal of discussion about what is allowed through and what is not. The short answer is that the stuff from Ikea is probably above your entitlement, and in any case there is discussion about what is or is not "personal goods". You night sail through, or you might have the lot confiscated.

I would advise you to wait till the dust settles before you start carting furniture from the south.

Although there is no Ikea in the south, there are lots of furniture outlets in the North. Do a bit of window shopping and check out some prices.

Ian