I'm embarrassed to ask this, but here goes; Im just returning to building
models, and I never built ships before. My question is;
with these small scale ships 1/700 in my case, what is the
best way to fill in the gap between the hull and deck, without
obliterating detail?
Many thanks. I'm building the Tamiya 1/700 British E-class.

I was moderately successful with super glue. The liquid type, not the gel type. Run some glue into the gap, paint silver, tape off the details, sand, repeat as necessary. The silver paint will show you where you still need to fill a gap.

Jim

Thank you. I tried this, but could never get an even finish. I
kept sanding, filling, sanding..........
The surface didn't even out before I managed to sand where I shouldn't
have

I'll keep at it and see what happens!

Scott, post this over a model shipwrights and you should get more information and response.