The Velux to the rear are Planning Exempt.
The Velux to the front requires Planning or Retention in your case.
Lets say you engaged someone today to sort out the Retention Application.
The next week or 2 would be spent surveying the property, arranging Newspaper notice, OSi Maps, prints, Site Notice etc
Once lodged, you will get a decision in 8 weeks, that's your Notification of Decision.
Theres a 4 week appeal period now.
4 Weeks later, you get the Final Grant of Permission, and then you can get your Engineer to issue you with a cert of compliance with planning, which you give to the other side.
Where are you based?