Move .nhsuk overrides to new scss file and update layout#1279

AnjuJose011 merged 2 commits intoRCTechnologyEnhancedLearning/LearningHub.Nhs.WebUI:RCfrom

Develop/Features/TD-5838-move-overridesTechnologyEnhancedLearning/LearningHub.Nhs.WebUI:Develop/Features/TD-5838-move-overridesCopy head branch name to clipboard