As the victim of a Paedophile in my youth and seeing many cases now brought to justice, I believe that stopping convicted sex offenders from travelling to other countries where child sex can be bought would prevent many offences.
You may be interested in these active petitions
It is known that many Paedophiles travel outside of the UK where sex of children can easily be purchased and upon a sex offender being convicted in the UK if the government were to prevent that person leaving the UK it would reduce children being abused outside of the UK.