All the usual things...

[#1]

...intermittently noisy phone line, rising noise margin, dropping ADSL speed.
Plus now, every time I start the Plusnet TG582n router, the ADSL connects OK but I have to 'manually' start the Internet connection rather than this starting automatically.  Anyone know what the solution is? (To the failure to automatically connect to the Internet)
TIA.

[#2]

If you have a noisy phone line, you need to start there and get it reported, so someone can have a look and get it fixed. Once that's quiet and reliamble, it would be on to the other issues if they still exist.

[#3]

If at all possible I would very much like to have my line reset. Thank you.

[#4]

no chance until you get the noisy line sorted out as it will just go back to horrible after the reset

[#5]

Hello there. I would recommend first plugging your phone & router into your test socket and if the noise continues to persist, we would need to book a line engineer to investigate the fault as this would likely be the underlying issue to any faults with the broadband.