These curtains would look best professionally made. Are you wanting sheers or fully lined curtains? I would recommend choosing wide width curtain fabric 300cm this will be more cost effective than 140cm wide.

You can have your track mounted to the ceiling. If you have an interior designer or curtain company quote they would recommend the best solution. If the extension isn't built yet you can ask the builder to allow for an area to fix your track. Do you have any wall space on either side of the windows to allow for what's called the stack back ( where the curtains need to sit when open) You don't want this getting in the way of the door. Do you have any drawings of the windows?

Hi I was thinking of a sheer type of curtain to add a bit of luxury. There will be integrated blinds in the doors so I don't need curtains to block out the light etc. The extension is not up yet so I could se if the builder could work out a way to leave room for a ceiling track. The whole extension is going to be 8m x 6.5m and the doors are 4m x 3m so there's plenty of room to make sure curtains are out of the way of door openings. Do you know if it would be more cost effective to have a ceiling track instead of a fixed curtain rail. I think I will get a curtain supplier/fitter to take a look once extension is up.
Thanks for your advice.
Kirsty

Hello Kirsty have a read through this website it has great images and information about track types. Yes there are ceiling tracks that will be more cost effective than a poles. It needs to be functional more than decorative let the fabric do the glam. http://www.bradleycollection.com/bespoke-track-collection/

Re: fabric here's some affordable ideas

http://warwick.co.uk/the-collections/breeze - I like the linen blends.

http://warwick.co.uk/qualities/valencia

For a little more lux check this french brand out these are gorgeous. http://www.casamance.fr/default.aspx they have great images.

Hope this helps.

I'll check them out this weekend thanks for your help