You can try any online retailer of plastic kits.
Just google it- im sure Youll find it.
To reduce the cost of shiping try the shops closer home.
The extras You need to order seperately- depends what You like from Your model.
The new VII C from Revell is excellent kit, and will bring joy to the modeller straight from box. To enhance it further get the deck from White Ensign Models, and photoetch set from Eduard.
White Ensign Models do sell original set of paints based on the chips of paints from actual boats of kriegsmarine.
Ask Bill Nichols- i believe hes started his VII C.
Good Luck.
Get the links of the shops in mention from my sig.