You need to fill in the forms. Online will telol you exactly which forms you need and I think (although may have been inland revenue site) you can order the forms online. Transfered a plate last year adn it took about three weeks. You'll get the certificate of ownership back which is valid for a set time so's that you can get a plate made up - then sometime after that you'll get the new log book.
don't even bother phoning dvla - waste of time and money.
Go into the DVLA office in Sheffield. Take your current V5, Insurance, MOT if applicable & VEL from the donor vehicle. If you already have the new vehicle registered to you take the same for that. If you just want to place it on retention for the time being no need. The forms you need will be in the reception area, fill them in while you wait. Costs £80 to transfer it to another vehicle or £105 to place it on retention - the subsequent transfer is covered in that fee. It isn't sorted on the day, it usualy takes 2 to 3 days through the post. Don't go down to Nottingham to do it, they are currently on a 7 - 8 day turnaround for the same thing. Can't be done on line AFAIK
There is a letter about this in the 'Expert Advice' column in the Daily Telegraph today (Sat).
There used to be a 'while you wait service' but that has now gone in the interest of service improvements.
Initially the VRO were taking two to three days to turn the forms around but now that has lengthen to anything from seven to ten days as Andy also indicated.
Causes all sorts of timing problems for people buying and selling and the impact on the timing of insurance etc.