@JeanW That's correct, the CSP that is placed outside the property is where the fibre is spliced before entry. It is totally impossible to splice a fibre off a set of ladders. That is why it will be placed at street level.
I am afraid you will never be able to stop anyone cutting your fibre cable. It does not matter how much you protect it on your premises if anyone is that determined to cut your fibre they would cut it back in the openreach network. Have come across many instances of intruders lifting up a footway box and using a hacksaw or cable croppers and cutting every cable in the box.
@JeanW Not wishing to be rude, but an end of terrace house on the street is hardly likely to be a prime target for the type of burglary that necessitates cutting of phone lines.
They could currently simply cut your connection now with an axe through the underground cable going up the pole feeding your current overhead line if they were that determined.