for me the key wording is
"to disclose, where practicable, the content of communications or secondary data in an intelligible form and to remove electronic protection applied by or on behalf of the telecommunications operator to the communications or data"
So your ISP who may be using l2tp needs to be able to provide the Gov with an unencrypted copy of your traffic with 24 hours. As they encrypt the traffic they have to be able to decrypt it (or if they use a 3rd party the 3rd party needs to be able to). Now the question is does say a VPN provider or an app the encrypts the data before transmission class as a telecommunications operator.
Add to that the complexity of what happens if I use an app or vpn provider thats not goverened by UK law, my ISP can not have the capability to decode that traffic, and they cant demand the app/vpn provider supply unencrypted traffic. When will they go oh now you cant use these services because they are secure turning the user into the criminal.
This is where we need a telecommunications operator to stand up and say ok fine we will develop a service that is encrypted in such a manner that we do not have the technical cabability even under duress to decrypt. Sell that as a service to the public saying we care about privacy we use X technology, but oh dear UK gov we cant comply we would love to but its not possible. Will they be in breach of the law or would they be clear as its not "practicable".