hey, mistress! :--)

i would go to this web-page and download both FREE pdf-books, either as files or as hard-copy, or just read them on-line as U wish -
Free Downloads | Dog Star Daily

the books are *Before* and * After U Get Ur Pup* by Dunbar, DVM.
he has excellent advice on teaching pups a soft-mouth, AKA an inhibited bite.

Q re Ur pup - How old was he when he left his litter for Ur house?
pups under 49-days / preferably at least 56-days or 8-WO, have not had enuf time in active play with their siblings to learn an inhibited bite. i think (tho i do not Know) that under-age pups are less of a problem in the UK vs the USA, but it is a possibility -
i wondered.

GSDs are notorious, along with some other herding-breeds, for being snappy pups and very mouthy - grabbing clothing, hands, arms, ankles, etc. be thankful he is not a Corgi, LOL - trainers think biting Corgi is a redundant phrase, like pair of twins, LOL.
teaching him Tug-of-Peace can be a HUGE help in getting mouthing and bitey behavior under control! Training Your Labrador Retriever - Google Books

happy training,
--- terry

terry pride, APDT-Aus, apdt#1827, CVA, IPDTA, TDF