I think you would like Gordon Strong's book "Modern Homebrew Recipes". There are loads of recipes for all kinds of beers including a lot of "lager" styles. But it is also the tale of his struggle against "awful brewing water" very much like Dorset's water. He has hit on the method of using reverse osmosis water all the time and adjusting it with phosphoric acid to get a liquor with pH around 5.5, which when he's added a minimum of appropriate calcium salts for the style, brings his mash pH to 5.1-5.3, which is pretty much spot on.
I haven't finished reading this fascinating book but he points out that a lot of German recipes are constrained by "beer purity" laws, which are not a constraint on the home brewer so he can, for example, use a flavourless mineral acid instead of acidulated malt and complicated mashing procedures to get the results he wants.
Two caveats: his batch sizes vary and they are declared in gallons and litres, but he adjusts his water with a quarter of a teaspoon of 10% phosphoric acid in 5 gallons- these are US gallons where 5 glallons is 19 litres; secondly, it's not clear whether he treats all his water this way or just his mash water.
Phosphoric acid is usually supplied at 75% or 80% strength and will need diluting. Be careful doing this, diluting acids can be tricky- you need to add the acid to the water and not vice-versa.