New toilet and waste pipes

[adg7]

I’m replacing the toilet in my house and want some advice on the waste pipes,

 

the existing format (see images) has a pan connected which seems to wrap around the waste rather than go into it, whereas I believe they usually insert into the waste pipe. It then seems to have another length of pipe connected to actual waste by a connector.

 

I want to know how much of this set up I need to replace for my new toilet and best items. I’m guessing I need to cut that pipe back and run a new length ending in a 90 degree bend that a new pan connector could fit into as currently there’s no where for a pan connector to fit into.
 

my new toilet is back to wall (spec below) I plan on boxing in waste and toilet will go to back of the tile board. So I guess I want the 90 degree bend to come out of boxing for the pan connector to go into.

 

very much a diyer and willing to get plumber in to do this section if I’m biting of more than I can chew

[stu w]

Some back to wall toilets are rear entry connection only , and not from the side .

You may have to build a small  stud wall section to bring it all out to make that particular toilet work with a standard 90 pan connector behind in the boxing section 

[Conor]

Yeah, a close coupled toilet won't work. You'll struggle to get a modern toilet that'll fit there unless you build a false wall, to the depth of the existing 90⁰ bend, up to the height of the cistern.

[adg7]

Sorry I probably explained that badly, I intend to build a small stud that the 90 degree bend would come through and the cistern would sit against.

 

I was more interested in how I would adapt that piping to fit a pan connector as the existing 90 bend appears to be part of the existing pan connector, but due to the spigot being recessed on the new toilet, would not be suitable to be reused in this situation