Properties buit since 2005 generally have composite doors. Those are usually a GRP ( glass reinforced plastic ) skin or a Steel skin.

A Sureflap unit supplied and fitted into a:-  GRP door - £160,  Steel Skin door - £190. USE A MAGNET TO TELL THE DIFFERENCE

 Traditional wooden doors and modern engineered doors are quite difficult to cut, but not impossible. They do attract a premium for the additional cutting time. Supply and fit a Sureflap into an Engineered Oak Door or Solidor - from £180.

Up and Over garage doors  - send pic. Relocate letterbox then fit catflap. 

 PETDOOR CONNECT and CATFLAP CONNECT - you have full remote control over the catflap. App on your phone tells you when each cat is IN or OUT. Lets you lock the flap via App on your phone in the event of a Thunderstorm or Fireworks, from anywhere.   Can go in ANY door or Wall !