Marcel, any import from the USA WILL be LIABLE for import duties, yes. These could be as much as 20% of the declared value of the item, PLUS an "Administration fee" which the carrier may choose to levy, for the privilege of doing the government's tax collecting duties. That could be GBP £10-20. Having said that, you MIGHT WELL get away without paying anything, but you should factor it into your calculations.
Having said THAT, doesn't this offer from the USA seem a tad TOO GOOD TO BE TRUE? Be aware that Fluke probably wouldn't offer their "lifetime support" (which, granted most of us never need to call upon, anyway), for such "grey" imports.