Peer-to-peer learning is considered highly effective. That is one reason, why the TAIEX-EIR PEER 2 PEER tool was developed (https://environment.ec.europa.eu/law-and-governance/environmental-implementation-review/peer-2-peer_en).

The website offers insights on European practitioner networks, which could often provide helpful information and support offers.

“European environmental inspectors, police officers, prosecutors, judges, auditors and heads of environmental protection agencies have formed separate networks to help them with their work. The networks enable knowledge, expertise and best practices to be shared. 

The European Union Network for the Implementation and Enforcement of Environmental Law (IMPEL) is an international non-profit association of the environmental authorities of EU Member States, and acceding and candidate countries of the EU, EEA and EFTA countries. The IMPEL Review Initiative Tool is a voluntary peer review where environmental authorities of IMPEL member countries help each other to improve the implementation of EU environmental law.
Associations of national, regional and local authorities promoting exchange of experience and good practice in environmental implementation are amongst others: 

• ICLEI – Local Governments for Sustainability 
• Eurocities 
• CCRE-CEMR – Council of European Municipalities and Regions 
• AER – Assembly of European Regions 
• ENCORE – the Environmental Conference of the Regions of Europe 
• ACR+ – Association for Cities and Regions for sustainable resource management 
• Municipal Waste Europe 
• Covenant of Majors for Climate & Energy 
• Aqua Publica Europea “

(Source: https://environment.ec.europa.eu/law-and-governance/environmental-implementation-review/peer-2-peer_en)