dose Imperial and CASS are very strict on GMAT/GRE ?

I have a strong CV + good recommendations. can I get accepted without taking a GMAT test ?

The GMAT is required.

Yes, these schools are both very strict, certainly for their full-time MBA admissions.

For EMBA programs, business schools will be a bit more lenient and may waive the GMAT requirements for executives with substantial work experience. But in terms of full-time MBAs in the UK - especially those ranked in the FT - you'll most likely need to take the GMAT. Lower tier schools like maybe Ashridge might be more flexible.