Thanks to all for replying.
Can't leave the cat flap open, other cats get inside and scare mine to death! (it has happened , I did this the first time...)
My cats are 10 years old, have use cat flaps always, in summer and winter, and always enjoy being free. I would like to be the same way, we live in a safe neighbourhood and i don't want them to be inside cats.
There no space for the cat litter in the house, it's in the bathroom now, but the bathroom is so small the tray uses al the space, and we can't use the bathroom! No space in the kitchen either, and i don't want to have it in the living room (there aren't more rooms, upstaris only bedroom and all carpeted).
In the previous house (not the one they grew up, just one we lived for 2 years), they went throught the catflap to the garage, and then to the back garden, which was more private. Here the cat flap is on the front door, and they have to walk all the way round the house to get to the back garden. I guess they don't like this.. but it's not possible at the moment to put a cat flap anywhere else.
I can leave the tray inside for a bit longer, but i'm worried she will never learn to go outside, i've even put the tray just on the other side of the front door (so she could smell it), but she won't cross the cat flap to use it, doing her things inside....