As recommended by Rick, we have availed ourselves of local tour guides when traveling with great success - worth the price. Looking for recommendations for private guides in Windsor - we will be there for 3 days so looking for guide services that go beyond Windsor.
Check London Walks. www.walks.com
https://www.walks.com/our-walks/windsor-castle-eton/
Before Covid i know they had a tour. Have to research to see if it’s still being offered.