Your lease will outline whether the freeholder has any responsibility for repairs. If you own a leasehold flat the freeholder may be responsible for repairs to the structure of the building, or shared areas. If you own a leasehold house it is unlikely that your freeholder will be responsible for repairs.
You should report any damage or disrepair to your landlord immediately. It's always a good idea to follow up any reports you make over the phone or in person with a letter so both you and your landlord have a record of any work that needs to be done.
It can be tempting to stop paying rent if you feel the property you are renting is not up to standard or the landlord is not sticking to the tenancy agreement. This is a risky procedure as your landlord may try to evict you if you stop paying rent.
There is a fitness standard that all privately rented accommodation must meet. If the state of your home is making you ill or causing a public health issue, there are agencies you can contact who can make your landlord carry out repairs. The fitness standard is quite low so often only homes in serious disrepair will fail to meet this.