Hey there and welcome to the Samsung UK and EU Community Customer to Customer Forum
If I'm understanding you correctly, you haven't paid your Care+ so your policy has been cancelled?
If this is the case, having the original certificate won't provide you with cover if you need to make a claim.
You will need to reach out to Samsung Care+ to see if you can make up the missing payments and keep your policy (they may say no if you've missed several payments)
S24 Ultra