I did the patch on engine side first (below the brake servo) but welded it from below as access was easier - partly from the pedals side but mostly from in the wheelarch.
Then I welded the patch below it, mainly from the wheel side but also a...
Take a load of pictures, post them online (here if allowed, or ebay, or autotrader) to get the biggest potential audience.
Be truthful about the dodgy bits as well as the good bits.
If you Can't get an MoT without spending any money, then you...
Water does get into that spot on 3 sides -
1 condensation / leaks just above the carpet/ insulation, around the weld-point
2 in the wheelarch & partly covered by the liner, which can trap moisture-laden dirt against the joint
3 inside the engine...
Mine had holes high and low...
The low one was easy enough, but the top one was right where the bulkhead met the inner wing.
Managed to weld it up, but was so relieved to be finished I forgot to take pictures.
Relieved as in, loads of smoke...