I do all my own work...so it's hard to advise someone who is paying someone. I know how much work I'd do, and how far I would take it...and also if I cut any corners etc or not.
Paying someone and not seeing what they are doing, you will not have that option unless you stand over and watch them which isnt an option.

And until you cut it open to see how far the rust extends....you do not know.

But if you just want the external visible parts patched up, which is basically all anyone would do for a basic MOT pass....then the job gets much faster and easier. But maybe not what some would deem as the correct job. And likewise for a crude patch just welded over the top as most will do, as opposed to cutting and trying to replicate the area removed so it looks reasonably original.

It all goes back to how fussy do you want to be ? Is it just an MOT repair you want or need, or is a restoration type repair you'd like to last as long as possible ?
Realistically how much longer do you expect to keep the car ? Does any repair need to be fussy or just quick ?