I think you are way overestimating 1600s florence and underestimating 1600s england.
> England is on the edge of Europe, quite provincial, not in great power.
We are talking 1600s england, not 600s england. During Cromwell's time, england was easily a major european power settling colonies in the new world. Far more powerful and far more important that italian city-states like florence.
> To go to Italy was to put yourself right in the centre of European culture
By the time cromwell was born, the italian renaissance was a distant memory. Shakespeare was the one advancing european culture, not dante.
> Especially Florence, where Cromwell ended up, was the epicentre of civilisation and culture.
No. The epicenter of civilization and culture moved west and north of florence by cromwell's time. Spain, France, Netherlands, England, etc were the new drivers of european civilization. Not florence, not italy.
> not just speaking Italian but a bit of German a bit of Spanish, fluent French and also reading Latin,
Pretty much what most educated europeans could do.