不論是否load bearing wall, 只要你一郁塊牆, 係應該就算無full planning permission, 都應該要有 lawful development certificate. 就算無 lawful development certificate, 都一定要notify building control 攞番approval
https://www.planningportal.co.uk/permission/common-projects/internal-walls/what-building-regulations-apply-to-internal-walls