Question re Welding - Focus TDCi (2002)

[HT281]

Evening,

I discovered today while looking over the car prior to the MOT that I've got a hole in the rear of the o/s outer sill where it joins the wheel arch. I'm getting it patched this weekend.

I was wondering, are there any other precautions needed other than disconnecting the battery?

Will the ECU's be ok?