Although I'm not a qualified electrician, I've done a fair bit of
extra wiring in my house: extra sockets plus a 6mm feed to an electric
shower and a 6mm feed to a cooker, etc. I did it all myself and it has
proved 100% satisfactory.

Do such mods nowadays have to, by law, be done by a qualified
electrician and/or done with buildings control approval?

The house is split into two flats and I now want to split the cirquit
into two: one for each flat. If I do it all myself, will I encounter
problems when selling the property soon afterwards?

I should also mention that when I bought the house in 1990, the wiring
looked a bit amateurish to start with: the under-floor connections had
all been done with 'chocolate blocks' for example. However, I've never
had a problem with any of it.

Thanks for any clarification.

PG