Update - my friend has decided to continue the tiles around the walls, and says thanks to all of you for your helpful input. I will make sure he provides me an after photo next week. :)

Thank you for all the ideas. Sometimes you think about something so much you can't see solutions. Like the ideas of umbrellas or awnings. We have 80 mm of the timber beam available to put an awning on. I think they're wider than that.☹️☹️ (There is a bolt in the beam that protrudes 2cm, it's not easily seen in photo as it is painted cream). An awning would need to sit underneath this bolt. The panels are plastic not glass and their track would need to be clear for when we open the pergola up, which we do during summer on long hot spells. We did plant callistemons about 3 -4 m away but they have not grown according to plan...lol I'm thinking the most achievable solution is a cantilevered umbrella. I think we'd need to concrete the base into the ground and remove the pole during winter. The brick area is a play area - netball etc. Any pros or cons to this idea?

any gas log fireplace should have very specific instructions for safe installation with measurements for distance from back and side walls, height above floor and height of any mantlepiece above the front of the heater and details of the correct method to enclose the flue..first check these instructions and then decorative finishes will be much easier to decide...if you haven't chosen your heater yet all the instructions should be available on line and this will also help decide the best heater for the space available

I am planning on building a glass house around 4x3 metres. I plan on having the rear and one side fully enclosed with the front and one side glass panels. I would like a pitched roof with glass on one side. I am looking for a builder that can work with the existing concrete foundation.