Tenants Rights to upgrade fixtures n fittings??? UK only please......?

I have been renting my property for almost 7 years now. In that time we have decorated and added curtain poles etc., that were needed (as there were none) - we have decided that we would like to get new carpets (present carpets are about 30 years old (old RAF houses)) and new bathroom suite (30 yrs old too) because we plan to stay where we are for at least another 5-10 years (we have young family and like our home and area) - our tenancy is a long term tenancy and the landlord has no intention of every kicking us out - unless of course we default in rent or abuse the home. We plan to pay for this ourselves, but what i would like to know is, should our landlord actually pay for the refurbishments or contribute towards this? If we pay for it ourselves would he automatically increase our rent - because we will have improved the property (our rent has never been increased since we moved in).