There is no time difference between the UK and Fuerteventura. Both places are part of the Western European Timezone (WET) along with Ireland, Portugal (except the Azores), the Faroe Islands and Iceland.
All of those areas use daylight savings time in the summer – except Iceland, which observes the same time throughout the year (the clocks do not go backwards or forwards in the Autumn or Spring).
There are several different names and standards for these time zones (e.g. Greenwich Mean Time (GMT), Irish Standard Time (IST), British Summer Time (BST) etc.), however, the clocks change on the same days in Fuerteventura as in the UK and Ireland, so for all intents and purposes, the time is same in both places throughout the year.
Mainland Spain, on the other hand, is in a different time zone to the Canary Islands and uses Central European Time (CET), which is one hour ahead of the Canary Islands. This has been the case since the Second World War, when Franco switched Spain from GMT to CET in solidarity with Nazi Germany. In recent years, the Spanish Government has proposed that the country change back to GMT, which is the natural time zone for the country according to its Westerly geographic position.
Something to be aware of during your visit to Fuerteventura, is that the mobile phone operators often use the time-zone of mainland Spain (CET). This means that your phone may show the incorrect time, and therefore have unwanted effects on alarms!