Hiya @James_W & Welcome Back To The Cuckoo Community !!! even if its for a Brief Stint or Not.
Looking at your Master Socket images as it is id say its only 1 or 2 generations back to the current Openreach Filtered model which is a NTE 5C mk4 with two push clips on the side instead of the secure screws on the previous version (see below the new version).
I Actually prefer the 2 screw version of the lower faceplate version of this however.
Based on what your saying it sounds to me that your property is only receiving ADSL style speeds which are up to 8mb which can result in stable speeds of around 5mb or less if your lucky.
Im sure your aware of my Famous Link below (If your the James White Im Thinking of)
to check the Exchange / Roadside Cabinet (RSC) / Pole Capacity to see what tech is available for your area.
As @RyanK92 has said to actually get Openreach to move forward and deploy the FTTC equipment it does need you to go and register your address & details as an end user on the link below for email updates on whats being planned and make them look at your area when they get a lot of interest from people.
Fill in this checker and at the end of it they will tell you if theres any plans or advise you about the community full fibre partnership and updates form that will be partially filled in from the checker so just complete this form to keep up to date or follow through if your brave enough to rally the community in your area to sign up and get BT to act sooner but this is probably the best way to be honest.
Cuckoo Broadband Requires FTTC To be present in your area and also the exchange to be LLU unlocked to be able to sign up succesfully but any provider offering up to 8mb connections should be able to accomodate your line but be warned this is slowly being phased out.
If you submit a screenshot of the Results from the Wholesale Checker link above but crop the image at the top before submitting the image to this thread from the checker it will show the community whats in your exchange technology wise and potential speeds.
Going back to the socket images above those two extra wires on the right side of your front faceplate are normally line extension wires to the other rooms in your place eg…kitchen or bedroom or lounge as an example to plug in your home phone or router in another room and there should be another socket somewhere but for reference when you remove the lower half of the master socket it basically disconnects these wires as there not connected in the main test socket where you have currently put your broadband filter dongle. Which if im not mistaken is an “excelsus z blocker filter model z-350uk”.
Things are changing in the next 5 years with the Network Infrastructure I believe but I suspect the copper infrastructure will still be around for quite some time.