It depends totally on what you're doing.

Your statement regarding never having had to deal with this stuff before suggests maybe you dont know what you're doing and are best leaving it to experts?

Failing that.

What are you knocking down.

Building regs will only apply for certain things and in certain situations, like sale of the house or building of an extension.

If the house is listed as 3 bed, 2 living room house and you make it 2 bed or through lounge the solicitor may advise the purchaser to have building regs approval restrospectivly if you dont have it.

If you do the job right in the first place you wont have any issues in this case anyway.

So...

What are you doing??
Whats above the wall you're removing??

Jake