I'm returning to work after a long illness, during my time off I got a cat who's 1 and I have a kitten who's about 3 months little kitten isn't allowed out yet as we've only had him 2 weeks, the cat comes in the window at different times of the day and if I'm going out I leave utility window open for her or sometimes if she's in when I'm leaving I just leave her in she's happy but I don't want to be gone all day and leaving the window open I want to get a cat flap I don't want to be leaving doors locked in case of burglary I want the cat to have access to the house as she has a cat tree in sitting room and her bed up high in kitchen she likes both, problem is our back door is a door that you lock by pulling up the handle and locks come out of the side is this even suitable for a cat flap all my doors are like this would we take panel then there might be a metal locks going through it so cat flap can't go in there?