How do I bathroom / kitchen / extension? etc.

Hi all - been quoted £8000 for the following work and we're struggling to get any other builders to even quote to provide us some context for the price. Any idea whether it seems reasonable?

• Supply and install skylight (pitched roof) and reconfigure internal ceiling to match
  
• Supply and install bigger white uPVC window (back wall)
  
• Re-lay sub-base and top felt covering on the flat roof, supply and install new gutters, fascia and soffit boards
  
• Supply and install 10 LED spotlights
  
• Make outside walls around pipework water tidy and fix outside pipework
  
• Strip out old box around pipework and make it good (make a new one as tight as possible)
  
• Hack off wet (water damaged) plaster and make it good after
  
• Repair the ceiling, prepare it for decoration and decoration works (white color paints included)
  
• Make good around the garden double door
  
• Relevant rubbish removal