I would suggest everyone stops contributing to this topic. The OP isn't prepared to listen to the advice being given, nor provide us with the details of the existing sockets etc. which would allow us to recommend the best way forward (technically and economically). If we do answer his questions and it all goes wrong he's likely to start blaming us.
... especially when admin go into troll mode rather than helping...
I would suggest everyone stops contributing to this topic. The OP has obviously made his mind up on how he wants to do it and isn't prepared to listen to the advice being given, nor provide us with the details of the existing sockets etc. which would allow us to recommend the best way forward (technically and economically). If we do answer his questions and it all goes wrong he's likely to start blaming us.
I've already answered above, it doesn't get any simpler! Assuming you have an incoming line currently terminated to one master socket you need to replace that with a Mk4 :-https://www.run-it-direct.co.uk/adsl-vdsl-faceplates/mk4btopenreachvdslsocket/You may need a back box if you don't already have one :-https://www.run-it-direct.co.uk/euro-faceplates-backboxes/22mmbackbox/That will give you a new filtered master socket for your phone. For the extension you just need this kit :-https://www.run-it-direct.co.uk/vdsl-adsl-extension-kits/vdslextensionkit10m/& add the telephone option at the bottom of the page. That gives you an extension socket with filtered telephone & unfiltered broadband. Job done!
No, you need a filter at the master socket to be able to plug a phone in, as you wanted phone & data on the extension the Mk4 will handle this too.
This could cause a bridge tap as the router is supposed to be the first device on the line and in the first socket on the line. However you also have a junction box doing who knows what.
Broadband side-CONNECTED TO UNFILTEREDPhone side-CONNECTED TO FILTEREDThe extension is doing NOTHING, the MK4 is providing FILTERED & UNFILTERED outlets.