Private plate owner here, Car dealers seem to be able to transfer numbers with the speed of summer lightning. Us lesser mortals, whatever the website says, are best served by queuing in the local DVLA office. I'm pretty sure that you can do what you want to do, but that leaves the subject of getting hold of the plate.
A colleague of mine handles the advertising for one of those dealers that take half pages in the Sunday papers, no promises at all, but I may just be seeing him at lunchtime.
If you PM me the full number that you want, I'll try and get an opinion.

N.B. A used car dealer that I knew some years ago, used to have his initial followed by one on his cars, he reckoned that he would have to pay the maximum fine 40 times to come up with the cost of the cherished number.