Buying old house to renovate

Hi all, as per thread title, looking at buying a house which has been idle for 30 + years.

Current situation, no septic tank, no live electricity connection (although previously serviced by electricity), rectangular building, stone walls front, back and one side, gable end is single row of concrete blocks.

Walls seem structurally good visually, will be getting an engineer to verify the structure etc.

Current structure is 40 sq metres.

So my main questions are;

1) Septic tank, regards putting in a septic tank, I know I am going to get answers like speak to your local planning office, but I am on here looking to see if anyone has experience in similar situations and how they dealt with it and the process?


2)With the new building regs, from my reading if we were to extend to this building not exceeding 40sq m to the rear we would be exempt from requiring planning to do so and we would also not have the requirement of having to contract an assigned certifier.
Just wondering if everyone else reading of this is the same?

Any comments experiences anyone wishes to share on similar scenarios are very welcome, I am trying to gather as much information as possible before bringing in engineers etc and purchasing.

Thanks