I doubt you would need permission to change the chipboard, but your lease may set out permissable flooring and you should follow that. Older ones certainly specify what you can and cannot use.
I have more doubts about the units, particularly if they are fixed and water or electric work is involved. Although the work is down to you, you are likely to need consent. See http://www.camden.gov.uk/ccm/content/housing/council-tenants-and-leaseholders/homeownership/making-improvements-to-your-property/, which specifically says consent to change kitchen units is needed and how you get it.
It should not be onerous.