If you look at the spring right at the top where it dissapears into the turret it may be obvious if it's snapped.

If they have snapped though it's always worth changing them in pairs and also get the top mounts changed at the same time as these can suffer due to the increased loads.

As an example the springs are between £50/60 a side and the top mounts are around £12 each. Go to ford with a chassis number to get the correct springs for your car.

Labour varies but it shouldn't be more than 3 hours even with issues but it's well worth it if you don't have industrial strength spring compressors as they are a bit long to do with halfords specials.

Also get your complete geometry checked with front and rear alignment done as there is all sorts of adjustment in the rears as well.