Welcome aboard Hunter!
No worries, your English is fine.
There are lots of after market kits available. The best Conning Tower/Sail/Bridge/Turm is by CMK, but is no longer available, though there must be some somewhere. Two excellent sources are White Ensign Models (WEM) and Models by Mickster.
WEM:
http://www.whiteensignmodels.com/ModelsxMickster:
http://www.modelsbymickster.com/There's aftermarket info at my U 557 site:
http://www.rokket.biz/models/modelsweb/rokket/u557/There WERE brass periscopes and gun barrells, turned on a CNC lathe, excellent quality, but the fellow (Steve Nuttall) making them died last year. A few places do similar, but it is hard to get good guns and scopes.
Hope this helps at least a little.
Keep us informed about what you need, and how your model is coming along.
Best,
Wink and all the sub modellers