Obviously have the sharp pointy end of the towed car on the towball end of the trailer mind.

I once towed a car a 'mere 2 miles' the wrong way AND crawling and it wasn't nice - never again.
Sure, to do this the 'legal way' you'll need a Transit or bigger van/truck/4x4.
You're going to go and get it anyway by the sounds of things so do it as "right" as you can
- goes without saying and all that and you're using a good sounding trailer, but...
chuck all the available weight of both cars in the middle/boot of the tow car - spare off
the towed car, trailer spare too PLUS the toolbox, jack etc of the kit you'll have with you - if you
hadn't planned to take any, it helps 'plant' the rear of the towcar and balancing the noseweight of
the trailer.
ENSURE THE TOWED CAR IS STRAPPED DOWN VERY SECURELY!!
Get some of the pukka wheel webbing jobbies from Machine Mart as they're a bargain price.
Should it all goes tits up, the plod cannot do you for insecure load - they specifically look at
trailers for this; I don't know how far you plan to tow but what I've always understood from
talking to a traffic guy is if you show you know what you're doing, taking extra care and
not playing silly beggars they'll leave you alone. If you're towing with a big heavy Xm (estate?)
and the car on the trailer is secure you should be OK.
Insurance is another different minefield. I'll wager they would want extra cover for the day
and then only if you'd be towing a far lighter car than the towcar and trailer weight combined.
Key words whilst towing a big heavy trailer - anticipation and planning. Take it easy!
Andrew