Have just consulted the interweb and have been overwhelmed by the choice of price points and features. We are looking to put a largish extension on the back of the kitchen and want to play around with what the space might look like before I involve an architect. I don’t mind spending some cash ~£100ish to get something that I can re-create the current space and then model different options of room size, layout etc before getting technical and getting quotes etc. Anyone have any hand one experience? THanks

There’s a few 2d cad packages that are free, but you’ve asked for 3d. Not so many. This may work, but not really for buildings, more mechanical CAD:
Design Spark Mechanical

Someone else may know of architectural packages.

(Also, £100 isn’t much in CAD terms)

Sketchup?

Qcad.
http://www.qcad.org/

Around £20, with a free download to try it out first.

Sketchup for sure if you don’t need to produce fully dimensioned architect’s drawings etc. (though it can do dimensions too if you need them). It’s ideal for playing about to see how options might look. Build your appliances, cupboards etc. as separate components and you can click and drag them around in 3D.

I used Sketchup to design my cabin

You don’t want a CAM package.
Unless your planning on machining it from a solid block of metal.

Will check out the options above. Yes only need the CAD part!

if you are going to use sketchup then be sure and go through some of the tutorials first. it will save much pain

Sketchup all the way, it is free (the non pro version is free forever).

watch a tutorial about how to make and use components in it and it will save you so much frustration! Simplest explanation of that is when you start making geometry and putting it together everything gets ‘stuck’ together, so if you make a cube, then another cube and put them right next to each other then try to move one away, it will be ‘stuck to the other and will pull it with it. However if you make a cube, make it a component, make another cube and make that another component, then sit them next to each other they will remain separate entities and not get stuck together, so you can still move them about separately.

I,d like to see the gcode for a extension!

another vote for sketchup

Student/30day evaluation of Autocad 3d or Revit

Draftsight is pretty good for a free 2D otherwise Sketchup for 3D.