You will be fine with English on the CP. The level of English spoken in Portugal is unexpectedly high - it is the European country that bucks the trend of English levels being higher in wealthier and geographically northern countries. According to the
2021 English Proficiency Index, Portugal's score is 'very high proficiency' and its country rank is No. 7 (among non-native speaking countries), one spot above Sweden. For comparison, France (No. 31) is one rung down at 'high proficiency', while Spain (No. 33) and Italy (No. 35) are one rung further down at 'moderate proficiency'.
Please don't try to speak Spanish to Portuguese people, as they do not like this. While the two countries are allies now, they have been rivals for most of the last 1000 years, including a period from 1580-1640 when Spain (Castile and León) took over the Portuguese crown. The fact that Portuguese people have their own, distinctly non-Spanish identity is one reason why Portugal ultimately regained and retained its independence while every other kingdom on the Iberian peninsula was eventually swallowed by Spain / Castile and León.
This was once written on the social media of Practice Portuguese (a podcast / learning platform for European Portuguese): ‘When you get to Portugal, you will notice that we love to show off our English skills. And of course, we love to help foreigners in need. So whenever you are having trouble finding a word, do not jump to Spanish please. Portugal and Spain are friends and neighbours but our languages are different, and we do not learn Spanish at school.’