Hi Stacey and
@Theresa have read up the post got to say as mot tester thats pretty done in .
I know the outer sills may be £130 a side but thats not the problem.
The rear inner sill leading on to the rear lower inner arch holed .
Also outer sill holed at the jacking point if the corrosion has spread right in there ( which it looks like it probably has) initially would require the panels off to assess the extent then if both sides the same major rebuild required.
Got to be honest if you are going to have to put it into a garage then a major bill awaits for a repair that may not last depending on how extensive and quality of the repair.
Guessing its a 1.9 (going by exhaust i can see in pic ) i would put the money into a new zed and take and bits you need from yours then sell for spares.