Help! 13pin to 12N Tow electrics adapter question

Hi, I'm brand new to the forum and to owning a range rover with a dealership fitted tow bar. It's the detachable type and the electric socket is behind the little removal panel above the tow bar slot.
My car has a european standard 13pin socket fitted.
The trailer I am about to buy has a 7 pin lead.
I have spoken to the LR dealer and they can supply an adapter for the princely sum of £45.00. Part no. VPLVT0064
I have looked on ebay and seen loads of other adapters that appear to do the job but my question is this.

How do I know that another cheaper option will fit onto the car, the cheaper alternatives all look a 'bit bulky' and I am worried I might buy one only to find it is too bulky to fit onto the socket. Has anyone had the same scenario? Alternatively, has anyone got the official part (VPLVT0064) who would like to sell it on?

Any help and advice would be very much appreciated.

Thanks

Halfords (Halfrauds as it is generally referred to) do one for £14.99. If it don't fit just take it back!!!!

You can also get adapter leads, normal caravan 13 pin plug with a 12N & 12S socket (you would only need to use the 12N for a basic trailer)

The Halfords 13 pin plug will NOT fit the Landy socket because the outside diameter of the plug is too big and is designed to be used with a screw-locking system

I have a 13 pin to 7 pin adaptor, never got to use it. Looks a bit like that.

If I can find it yours for £5 including postage (about £2.50-£3)

You can find very small adaptors on Ebay for about a fiver, I have 13 to 7 and vice versa to accomodate caravan & trailer on either the P38 or Transit.
Be aware that 13 pin to 7 pin will not give you the 7 S connections. Better to change the plug on the Trailer IMO unless you just want the basics.

There are two types of adaptors. One is a Y-cable with a 13 pin plug, short lengths of cable and 12N/12S sockets. This should work with any 13 pin socket as they use a regular plug.
http://www.amazon.co.uk/Maypole-603...405532162&sr=8-3&keywords=13+to+7+pin+adapter

The other type is basically a chunk of plastic in the form of a 13 pin plug on one side and a 12N plug on the other. This would be neater for a basic trailer.
http://www.amazon.co.uk/Waterproof-...405532162&sr=8-1&keywords=13+to+7+pin+adapter