For the Pat Coleby book - keep looking on
www.abebooks.co.uk too, as it is an older book.
The Pat coleby book recommends feeding barley rather than other grain, so you should be ok. With GG's you should watch out for their droppings if increasing the concentrate ration - when on too high proteins they quickly become runny. Shreds are not too high in protein, but are good energy. Lots of branches are also good (but labour intensive). My older GG doesn't eat cow dairy nuts, if yours do - they are good for milkers, but probably too protein rich for dry GG's.
Are you planning to put her back in kid this autumn?
I don't as such test for mastitis with any special kit - I find that if the milk goes slowly through the filter something is wrong... also somewhere in the goat section last year I described the washing-up liquid test that I do.