This list is not exhaustive as there will be tissue banks that we are not aware of, but for UK and Europe based researchers/clinicians or individuals considering donation, here are some links to brain tissue banks:
Newcastle Brain Tissue Resource: at the moment of writing, the only leukodystrophy related cases are 2 Krabbe Disease brains available
UCL Queen Square Brain Bank: contact them using this email address qsbbmtas@ucl.ac.uk
The Netherlands Brain Bank: a large collection of leukodystrophy cases
Alex TLC publishes a monthly research summary of recent leukodystrophy research and clinical trials. Visit their website to access article summaries accessible to the public and direct links to websites and articles.