Eu sugeriria algo como:
function! ForwardLookup()
" get next key pressed
let c = nr2char(getchar())
let old_search_pattern = @/
" Use of \V enables very-nonmagic pattern
exec 'normal /\c\V' . escape(c, '\/') . nr2char(0x0d)
let @/ = old_search_pattern
endfunction
nnoremap f :call ForwardLookup()<CR>