I know this is an old subject, but I feel I can add something useful to the repair process for the inner wheel arch as experienced by Lee in the photo above.
First thing, remove the back seat and rear seatbelt. The reason is because of the area marked by the red circle. If you weld in this area, chances are the weld may go through some seam sealer and inside the car and cause a fire. Actually, in my case, it did cause a fire. Anyway, onto the blue line marked on the photo. To save a lot of awkward welding, do a butt weld here. If you do a lap weld, you will find it a lot harder to weld as the petrol feed tube will be in the way. Actually, I removed the petrol tank and feeder tube and even then it was still hard to lap weld it. I should add, if you ever remove a seatbelt anchor bolt, never retract the seatbelt. Instead tie it to something to stop it retracting or it may never un-retract again. The other thing, place a wet towel over the weld area inside the car.
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