Hi Zoe,
Are you sitting comfortably ? Then I'll begin...
It's impossible to say precisely how your line is routed to the exchange without talking to a local Openreach engineer.
However there are several quite distinct methods that are employed.
Both have E-side cables usually (but not exclusively) routed via underground cables to the exchange.
In areas such as yours the D side cable is routed either in ducts, or worse still buried directly in the ground, to a point near your house.
At that point the cable is brought up the pole usually to a joint sleeve and then to a distribution box at the top, where individual two pair drop cables are looped across to the houses.
If there are more lines further on you will see another cable leaving the joint sleeve and going back underground along to the next pole.
Sometimes, and particularly in more rural areas, the cable will come above ground to the same type of joint sleeve and distribution box, but then the ongoing cable is daisy-chained above ground along to the next pole(s).
In other areas the same methods are used but every cable is run in ducts or in the ground all the way to your house.
In blocks of flats a large cable enters the building and smaller cables are distributed usually in a service shaft to individual apartments.
Other arrangements can be used; one such method is for a group of small drop cables to be all looped overhead, sometimes in parallel with the larger D side cable(s), along one or more spans before they go off to individual houses.
This method is used to reduce the number of joint sleeves as each joint is a potential source of unreliability especially when human intervention is necessary !
This might sound complicated but if you look at the poles and joint pits you can guess how the routes are connected.
If you are that keen you can PM me with an e-mail address and I'll send you pictures of our local horror stories !
Where FTTC is installed, link cables connect the new cabinets to the existing cabinets so the broadband signal is injected at that point rather than at the exchange.
I believe that most BT FTTC use a "shared metallic path facility" so the broadband signal is Teed in to the phone line but BT wholesale also offer a "Full Metallic Path Facility" so that other Communications Providers can have the E side pair totally disconnected at that point. This latter method is similar to the full LLU that providers such as TalkTalk use in the exchange.
Kind regards,
Walter