Body work/ rust question

So I just got back into a fox after getting rid of my 99 cobra (what a difference, haha)...

anyways, I was under the car a couple days ago to clean up and mark the balancer so that I can set the timing and low and behold, rust. Right behind the tire, under the firewall, at that genius seam, that from my reading, is fairly common. There is a small hole where it rusted through and the situation is the same on both sides.

Being as I have never welded and have no immediate access to one (eager to learn, but not spend the money to buy a welder) what are my options?

Do I just roll into a body shop and ask them to cut the bad spots out and put in new? Should i just go to any welding shop? Is it really that simple? Anybody wanna guess as to cost?
 
I have rust on my convertible in that very spot, driver side worse than passenger. I can weld panels and am interested in hearing what others have to say!

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I had a good sized hole there on my vert, once i ground away all the crap metal I could almost stick my hand up there. I had access to a nice mig at the time (I only have a tig that I cant weld to save my life with) and my carpet was out so it was no big deal at all. at that seam there were like three layers of rusty metal so I cut it all out and welded a peice to go right up the firewall a little and behind part of the frame part. I'd say maybe a 2 hour job with everything out of the way and all the tools and material right there
Heres a picture after I patched it and painted the bare metal and seam sealed the crap out of it
100_1181.webp