I cut out for the footwell extension a while back, but never got around to fitting rivnuts to the cover, so I marked and drilled for 6x M6 rivnuts. 5 of these come through into the footwell, where 1 goes into the master cylinder compartment. This was temporarily fitted, and will be finally fitted once the body shell has been put on.
Also, taking some pointers from Mark Turnbull's blog and Dale's blog, I decided to open out the footwell adjacent to the accelerator pedal. I may need to slightly modify this once the accelerator is fully in place, however I copied what Dale had done here. I will wait for the accelerator is in place and checked before applying glass fibre matting to the area. Thanks Mark & Dale!