Advise needed about visa/settlement route

Hi! My husband and I are in the current situation written below:

- I am a Dutch citizen with Dutch and British nationality (both by birth, I was born and raised in the Netherlands). My husband has the Dutch nationality. We were married in 2018 in the Netherlands and have lived in the Netherlands all our lives.

- I applied for my British passport which is going to be sent to me soon.
- We want to live in Scotland asap, at least when we find jobs. For me it isn't a problem, because of the British passport.
-We would like to move before the end of June, but Covid makes it difficult! So more realistic would be to move around August 2021

I am trying to figure out what would be the best route for my husband to take. He has been offered a job. Can he apply for the Surinder Singh route after I have received my British passport? Or does he need to apply for a spousal visa? Is this route also possible whilst we are still living in the Netherlands? Do we need to send all our papers to the UK or is there an office in the Netherlands? Is there anything else my husband needs to do after arriving in the UK? How long is the permit for? As you can see... a lot of questions. Hope there is someone who can give some advise.