Although the Canary Islands are not in the EU, they follow the same immigration rules as Spain. (i.e. as with all EU countries, your passport is valid for entry right up until midnight on the last day of its validity). There are only a few countries which require 6 months validity on a passport. EU law prevents any member state from imposing such a condition on any citizen of any EU country.
However, as your passport will expire next year anyway, you might as well renew it (with your new name on it) as soon as you return in January. If you're prepared to attend a Passport Office, you can obtain a guaranteed one week service for �97.
Alternatively, you could simply continue to use your maiden name until after the honeymoon. (There's no legal obligation upon you to change your name upon marriage). As long as your honeymoon tickets show your maiden name, it won't matter that your passport is still in your 'old' name.
Relevant links:
http://www.passport.gov.uk/passport_amending_m arried.asp
http://www.passport.gov.uk/apply-urgent-within -two-weeks.asp
http://www.passport.gov.uk/fees.asp
Chris