Citroen C3

Hi there. Just got a few question I need to ask. As I'm a complete noob and searching return nowt I can use. Got a Citroen C3 Desire. I don't have a key fob only a bog standard key that I use to manually lock/unlock the car. However I have noticed that it'll only unlock/lock the driver door and I've noticed this is standard with citroen. But not having a key fob to use, what am I meant to do? I know about the little lock thing on each of the door apart from the driver side but it's an hassel and I've got 3 kids.. Also there seems to be no method to lock the boot... Just wondering If I can buy a key fob off ebay or whatever sells them and program it to my car? But I've no idea which to buy and methods to use. A bit of direction and help would be greatly appreciate. Thanks EDIT - also, it's a 1.1 when at 70mph in 5th gear the rev is at 4k rpm. Is this normal because it a 1.1 or a fault?