Great space
Couple of thoughts.....
1. if you colourbond the front and sides up from ground 2 ft you will stop mice running through. YES mice do get through that size mesh.
2. mesh of that size catches feathers...I was told this valuable piece of info AFTER I meshed mine with some of that size mesh. Wont vacuum off or brush off easily, Burns off with hand held blowtorch. What guage mesh have you chosen ....try and go OVER 1mm into the 1.4 or more. The thin guage stuff ( inder 1mm ) from bunnings etc is very fine and hard on their feet, and does actually get opened up by hawks very easily.
I sourced my own mesh via a mesh suppler not the hardware store and was way cheaper.
3. Wood ? What type ? and will birds be able to chew it ? Metal c channel from bunnings 3 metres lengths is around $6-$7 a length.
Try sourcing your colourbond through a salvage yard or recycle at the tip...you can get new sheets for very little money there and all they may have is a few scratches easily touched up by a matching colour spraycan.