Where to start- removing a Parkray and surround

[Rosemadder]

We want to remove this Parkray, it has a back boiler connected to 4 radiators, the pump is located in the cupboard to the right. The system was last used around 5 years ago, until the chimney started to leak smoke into the attic, and the attics of adjoining properties (but that’s a separate issue, house was built around 1830). Anyway, where on Earth do we start?! I presume first we should get plumber and electrician to take care of that side of things.
Is it a mega job to remove all of this? Need some info so we can plan it well!
We would like to have a modern surround and a space for an electric fire (no gas here).
Thanks in advance.

 

[Terrywookfit]

It would take me a liesurely 3 hours to drain and remove back to the builders opening....But l have done hundreds.