near-side inner sill corroded (MOT)

Anyone have this issue? Got it as an advisory last year, car hasn't been driven all summer, taking it in again for MOT now (probably <300 miles since last MOT)

Hoping it passes, anyone know what I can expect as far as cost if not?

Obviously would be easier to tell if I had pictures, but a range of prices would be helpful so I know going into it

I don't remember them mentioning it at the time and they're funny about you being under the ramps now, so I'm not even sure which bit is rusted
It is not the rust they care for it are holes that are too big to view your Micra as passable for structural soundness or it is just their book rule on a hole that is too big but for this kind of rules where I live I can tell they are meant for safety and not for annoying car owners. I assume and would be surprised if not it is similar for you. For the rust, if it is still hard just get rid of the rust, put rust prevention in place (don't forget inside) and if you do that well you won't need a welder ever
I had serious (often every 3 years) welding for MOT inner outer sills and wheel arch came in around £400, but that was a fair bit.
I have a pre face lift and the sunroof drain holes drain into the sills, so it's often ongoing, unless I go the full on sill replacement! .
Got quoted £100 to fix it so not too bad, that was a week ago I dropped it off though and they've not called yet

got to be a big job so I must be getting my moneys worth