Hi all just bought a 2010 ford focus but still have my last car a 2000 mondeo cant part with it how sad is that but they are getting rare now in northern ireland only rust on her is drivers sill in front of rear wheel would this be hard to repair?

Has it rotted through, or is it just surface rust. If the latter I would grind it down, treat it and Hammerite the whole sill from front to back. If its rotten, then it will need welding.