The Gordon Strong book is really good for the most part and there's a lot of stuff he says about water treatment which I agree with (eg keep it simple, stop trying to replicate regional profiles, don't put too much emphasis on residual alkalinity, don't make adjustments unless you know what's there to begin with) but it is definitely an "American" approach to it, with much more emphasis on mash pH than calcium, a lot of talk about RO, suggesting soft water makes better beer, "minerally" tasting beer, and recommended additions that are far lower than I'd use. For example these are some of his recommended profiles:
Malty beer - 60ppm calcium, 107ppm chloride, ~0ppm sulphate
Hoppy beer - 60ppm calcium, 140ppm sulphate, ~0ppm chloride
Balanced beer - 60ppm calcium, 50ppm chloride, 70ppm sulphate
So I would recommend the book, but take the water section with a pinch of salt (but not so much as to make it minerally).