The Canary Islands are within the European Union (although they count as 'non-EU' for the purposes of bringing back booze and ciggies, because of their special tax status).
EU law obliges all EU countries to admit anyone who can prove that they're a citizen of an EU country (by producing a valid pasport or national ID card). Consequently, your passport is valid for entry into the Canary Islands (or any other part of the EU) right up until the very last second of its nominal validity.
Very few countries visited by British tourists have a 'minimum passport validity' rule. (Even the USA, which has some of the strictest immigration rules anywhere in the world, waives their normal '6 month rule' for UK passport holders). Those that do are usually only interested in ensuring that you leave their country before your passport expires (even if, for example, you have to spend additional time in that country because of being taken to hospital). Since you have the automatic right to live (and work) in any EU country, you never have to leave an EU country so it would be pointless having a 'minimum validity' rule.
Chris