new build flue

Hi.
I am building a single storey extension to form a kitchen and dining room.
My better half wants a central gas fire (contemporary sort) that can be see through from both sides (basically walk around).
I am planning on building a block plinth and building up a stack (floor to ceiling) with a flue in the middle and plaster boarding over it then skim. The flue will exit Marley melbourn roof tiles.
The gas fire she has seen is a B&Q effort which requires a class 1 flue.
Is this the sort of thing i can do myself or do i need expert help?.

Thanks

Providing a class 1 flue is not difficult but is notifyable work (as is your single story extension) & before you do anything, you need to check out the Regulations applicable to Combustion appliances;
http://www.planningportal.gov.uk/england/professionals/buildingregs/technicalguidance/bchpapartj/

Putting one fuel burning appliance with an open flue (fire) in a kitchen which contains another fuel burning appliance (cooker) + a now compulsory extract fan raises several issues around maintaining sufficient draught in the fire flue & not starving appliances of air needed for good combustion. You may also run into problems with fire regulations, depending on the location of the proposed fire. Other regulations govern the construction of hearths & provision of permanently open ventilators once the fire goes above a certain heat output.

Do not use plasterboard or Gypsum based plaster products in fire openings, for boxing in the flue or on the walls in the immediate area of the stove. Gypsum plaster & plaster board (including Fireline) will not withstand regular exposure to temperatures much above 50 degrees C, it will crack & fail in a very short time.

A walk around or fire open on 2 sides (in 2 different rooms) is a very nice idea & I had one very similar but after talking to LABC, the number of hoops I was going to have to jump through I, decided it was just going to be too much hassle. Will be much easier to fit a decorative fire instead.