Lots of great sites
Intro Word/phrases and pronunciation - https://www.learn-welsh.net/welshvocabulary
Intermediate Words/phrases and pronunciation - https://www.learn-welsh.net/welshvocabulary?level=secondary
Lots of words here - https://americymru.net/americymru/documentation/contents
BBC has lists for both North and South - http://www.bbc.co.uk/wales/welshathome/textversion/
SSiW Gair y Diwrnod - Gair y Diwrnod - Word of the Day
That should keep you going for awhile, Susan.