Yep that's correct, though to add that if you had a current rating you could do the approaches without a safety pilot if you wanted to. You'd just claim approaches conducted during your normal flying.
An IMC instructor should be ok, you're only using them to meet the IFR requirement.
FCL.620 IR
[...]
(c) Applicants who have completed a skill test for a multi-engine IR in a single-pilot multi-engine aeroplane for which a class rating is required shall also be issued with a single-engine IR for the single-engine aeroplane class or type ratings that they hold.