I think slim line sliding doors look more modern and you'll get more view of your garden. We were going to have bifolds but have now decided on sliding doors. Our opening is 4m and planning to have 3 doors. As your opening is quite large, you could have 3 door and once they are opened, you will still get a good size opening. We're having 35mm profiles but I think you can get even thinner ones. Are you have a flat roof or pitched roof?

Tell us which you prefer! Read more here: http://bit.ly/bifold-doors-vs-sliding-doors

It would depend on the house but I voted for the black. The grey could be effective too but I am not keen on the white personally

I’m getting an ultraline sliding door fitted in our new extension in a few weeks. 2.4 high x 4.4 wide. The frames are 20mm. It’s about £10k and I can’t remember off the top of my head whether that includes VAT (probably not unfortunately). But our number one goal with our extension is to connect our living space to our garden, so it feels right to prioritise budget for it. You don’t need a local company necessarily as national companies will have local agents who have product in their showrooms. This has been tricky over the last few months but we also looked at local friends’ houses last summer, where they had installed various different brands of sliders and bifolds, and were able to get a good feel for them from their gardens! Good luck with your research.