Hi, I am confident in the wiring of the flat there are just a few electrical items I am unsure about such as master/slave dimmers etc.Not sure what you mean by the notifiable bit. Get the tester to sort that.
Are you not doing the testing and notification Yourself? Really if your doing the works maybe you should do the testing.
Youve bought the regs book. That’s good, but there is a lot more to this than the regs book. It will not tell you how to wire a flat.
Q1 it’s up to you. Your call. There are a few threads on here regarding rcbo or rcd. Personal preference.
Q2 Identify what an A type or AC type is for? And fit appropriate for the circuits in question.
Q3 there are no legal requirements to fit heat or smoke alarms in domestic premises. There are issues with rental domestic in so far as the landlord has a duty of care to protect there tenants, but nothing written in law.
Q4 I would recommend the 450 and 1200. they are good heights. It’s the hieghts I used in my own property, but it’s up to you and your client.
Q5 &Q6 speak to your supplier.
Q7 I work out the cost of material then work out how many days it will take. £300 per day plus materials plus an extra 10%, but this varies depending on your needs and the local area.
For the AC / A type I thought it would be necessary for most circuits as they will be rings, lights, oven, hob, boiler... pretty sure they all use some sort of DC internally?