Removing gas fire, false chimney

TheCyclingProgrammer

Once in our new home, I intend to have the gas fire in the living room removed so I can mount the TV on the wall.

To ensure all wires are concealed, I intend to build a false stud frame around the existing chimney breast. I've got this all planned out down to 3D designs, how I'm going to wire it safely etc.

My question concerns the removal of the fire and how to deal with the actual chimney breast. We can remove the surround and hearth ourselves and I've had a quote from a gas safe engineer of £40 + VAT to remove and cap off the fire which seems very good to me.

I know that normally you would either brick up the opening (or frame and plasterboard it) and use an air brick and vent to ensure the chimney remains ventilated.

If I'm going to conceal the original chimney breast behind a stud wall, is this necessary? Can I safely just leave the actual chimney breast open and put a vent in the false wall instead? Or should I still at least board it up? If I do board/brick it up with an air brick I assume I'd still need a vent in the false wall? Also, does the vent have to be located at the front/bottom of the false breast or can I position it anywhere (ideally out of sight)?

Finally, is there anything else to consider? Should I have the chimney capped off? There will be no working fireplaces left in the house - all the other openings are properly sealed and vented but our survey indicated the chimney had no cowls. What should I be looking at price wise to have this done? Thanks.