The EU countries have systems in place to deal with such cases. It is, though, up to each EU country to decide whether and/or when it allows EU citizens to enter or exit their territory without a valid travel document.
Your embassy will be your first point of contact in case your pass gets lost or stolen. They can provide you with advice on how to proceed, and are able to issue emergency travel documents if deemed necessary. Please note that a police report usually needs to be filed before your embassy can proceed with this.
See the current rules and information (where available) and/or visit the websites of the authorities of the country you are travelling both from and to:
- Czech Republic
- Slovenia *
- United Kingdom
* Information not yet provided by national authorities