It depends on the design. Most units described are readily available.

This is a great space to work with. Since you have a good length, you can break the terrace into rooms.. with yew to divide the areas, or tall plants with shallow roots. Grow grass in curves and a pathway to lead visitors through the various rooms. Couple of ideas for garden 'rooms': Bamboo with golden stem or black stem as background, with charpai and 'moda' seating with cushions. A light under the foot of the bamboo, looking up will be alluring. Put up a trellis with fragrant climbers like jasmine and seating underneath on a part of the terrace which gets shade in the evening so you and your friends and family can relax. A dry garden with hardy plants like tall grass and Palm tree, pebbles on the ground to create the look. Plant a small flowering tree in one 'room' Add evocative lighting to create the mood in the evenings. As you can see there are many possibilities. Please ensure the ground is well protected from water seepage etc before you start planting. Also ensure the height of the periphery wall is taller for it to be safe for children and adults. Bear in mind the size of the plant, roots, sun and water needs before you choose your plants. Enjoy the creation..!

You can opt for the frame work of solid wood or waterproof plywood , polish it , can install lights at cross section , I don't know about the size and shape of your room . This way you can have ceiling fan also at the location you want . Easy and simple solution. will look elegant as well

Koel - I'm facing a similar problem. I don't want a false ceiling, even the most simple one, because of the following cons: 1. Decrease in natural ventilation: A false ceiling reduces the ceiling height. Taller ceilings allow more natural light and airflow. Even a 6-inch drop is a bummer. 2. No added aesthetics: The concrete ceiling we have is already super smooth and has a flawless finish. 3. No functional value if you don't need much AC time: I live in Bangalore, and there is hardly a summer. Even though I am on the top floor, the roof has white tiles, and even in summer, the house doesn't get warm. I hate the overuse of ACs because of the environmental concerns too. So, I don't see any functional value in a false ceiling for me. 4. Recessed can light casts terrible shadows: The small lights hidden inside the false ceilings are more like focussed lights because only the bottom is exposed. I hate the coarse light they create. 5. Groove for cove lights is an avenue for dust: A cove light with a groove will provide soft and even lighting, but, living in India, dust is everywhere, I and I prevent any hidden spots for dust collection. This is more of a health concern. However, my builder didn't provide many wire points in the ceiling, and with the fans in place, only one point is left for lights in the living room ceiling. I just need a few more points in the ceiling to add a few pendant lights and directed spotlights to create a calming light with a few highlights on some wall hangings. If you want some nice-looking lighting setup without a false ceiling, there are some fixtures that make the wires visible as a part of their design. These are some Nordic minimal style light fixtures, and they are available in Ikea. You can explore them. I have one more year to go, and I am keen on finding more lighting hacks to avoid a false ceiling.