One thing other answers have missed is that some ssds encrypt data before writing and obviously after reading (this prevents a swap the storage controller type attack) A secure erase on such a device consists of changing the read/write key. Takes milliseconds. Irrevocable (unless you find a way to read previous contents of the key storage)
In the UK there is a split between England and Wales and Scotland. “southern” UK trespass is a civil offence. Scotland it is criminal.
So in southern UK trespassers will most definitely not be prosecuted (the railway and power plant property are, iirc, the two exceptions because they have by-laws) but may be sued for damages, in Scotland they can be prosecuted.