Are you replacing like for like?
If so, you should be okay.
The regulations you mention are part P of the building regulations.
If you go to projects pages and search for part p it will explain what you can and can't do (notifiable or non-notifiable)
There may be a case of a minor works cert being needed though!
New installation are notifiable.
A New installation some example below
Installing new CU
Installing new circuit from the CU
Installing new protective devices on circuits at CU.
Most work done in special location (bath/shower rooms, saunas, garden area, outside locations etc...)
and kitchens will also need to be notified.
This can be done by you or someone you employ to do the work but must be done. A self cert electrician will do this for you via his scheme provider.
A lot of work involved in DIYing notifiable work and a fee is payable to building controls.
If you intend to add on to or extend an existing circuit providing not in a special location or kitchen.
a minor works cert will be needed but this is not notifiable but again minor works certs are not that easy for a DIYer.