Things to watch The type of lock you want has a single spindle so the handles on each side need to be in the same place (The type of lock handle fitted to front doors has two spindles and the handles are offset from each other. This allows the handles on each side to operate the lock/latch differently)
On double glazed upvc and composite doors the outside handle face-plate has no visible fixing screws for a thief to undo - the handle can be fixed from inside of the door. On the inside of the door the face-plate will have visible fixing screws which can be removed to access the fixing screws for the front face plate. The alternative arrangement is for a screw to go through a hole in the inside face-plate, through the door and to screw into the back of the outside face-plate. Again nothing for a thief to undo from outside of your property A pair of handles will be matched for this arrangement so just be aware which is considered to be fitted to the outside AND consider this may/will swap for left hand or right hand opening.
As stated before the distance between the lock mechanism hole and the spindle hole can vary so you need to carefully match each component you purchase
Example of what you may be looking for