Please register with CREST through here.
CREST Spell Bee Winter (CSBW)
https://www.crestolympiads.com/spellbee-winter-csbw
CREST English Olympiad (CEO)
https://www.crestolympiads.com/english-olympiad-ceo
CREST Science Olympiad (CSO)
https://www.crestolympiads.com/maths-olympiad-cmo#
CREST Mathematics Olympiad (CMO)
https://www.crestolympiads.com/maths-olympiad-cmo
CREST Cyber Olympiad (CCO)
https://www.crestolympiads.com/cyber-olympiad-cco
CREST Reasoning Olympiad (CRO)
Sample questions
https://www.crestolympiads.com/sample-papers
Syllabus
https://www.crestolympiads.com/syllabus
Marking Scheme