eBay and Craigslist finds

The Peugeot looks a nice bike and I would happily restore it and ride it!
My thoughts:

• It's a big bike so you'll want to be at least 6ft / 183cm tall
  
• Mudguard eyelets! So this could be a great winter/rain/commuter bike.
  
• The bike does not look abused. Parts look in good condition. Paint looks in good condition too and will buff up nice with some T Cut. With some wax afterwards you can get a great result. Or just clean it!
  
• It's French so will possibly require specific sizes of headset and/or bottom bracket and/or stem. This is only a problem if they need to be replaced (you might need a new bottom bracket and you may need to change the stem to make the bike fit you). The bike being originally sold in the UK perhaps makes it less likely to be unhelpful French sizing. And actually as it's British tubing then maybe you'll be luckier here and find that the sizes are more standard. I'd Google this and try to find a documented example somewhere.
  
• Obviously 531 tubing is great, but I'm not familiar enough with the French decals to determine whether the whole frame is 531 - i.e. main tubes plus all stays and forks - or only the main tubes are 531 and the rest is heavier tubing. It'll be nice either way though.
  
• Cast dropouts are a good sign. They indicate a higher quality frame than one built using dropouts stamped from sheet/plate steel.
  
• The chainrings do not look too shagged which is a good thing because you might struggle to find replacements - three-arm cranks are not typical. Though eBay can provide wonders!