Hi and welcome!
I can't give you specific advice regarding what's possible with your tattoo, but Black Garden Tattoo is a reputable shop with great artists for sure. So yeah, go and talk to them and feel free to roam this forum as well!
And if you need more recommendations for shops or artists in London, let us know...
welcome ! and WOW ! those two ideas "photography & the Navy" are way cool,that brings to mind so many ideas & possibilities of great tattoo art ! the right artist could do so much with those two ideas !