Actually, also a general question..

Isofix all fitted, seat in place. Now. I assume with the isofix I dont need to also then wrap the seatbelt round the seat ?!

More important question - does a 2005 Supercharged RRS have any airbags in the rear that I need to disable?!

I can answer your first question having just fitted mine in preparation for a pair of iminent arrivals!

You don't need to do anything with the seatbelt. A friend of ours doesn't have isofix and I don't know how he copes!

no air bags in the rear other than the curtain bags which you cans disable

unless your fitted a rear facing child seat in the front seat, then there should be no need to disarm the airbags, as its the dash one that throws the baby about if its goes off, the side ones offer proection from sidewards impact or glass

with seats that have the isofix 5 point harness you don't need to use the seat belts to hold the child in

IT'S BEST TO READ THE INSTRUCTIONS or SEEK FITMENT GUIDANCE IF UNSURE

Your local ROSPA centre should offer a free fitting service of child seats (don't bother with mothercare etc), well worth finding out when they are open.
You'd be amazed how many car seats don't fit properly, even manufactureres own/recommended ones!

They are not tied to manufacturer so will not favour one brand over the other, its the 'fit' that counts.
I went every time we got a new car when we had child seats in the car, sometimes the existing seat was fine, sometimes we had to get a new one.

For piece of mind I'd definitly look into it.  ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

The isofix clips are enough to anchor the seat (no need to clip the 3 point seatbelt on as well).

I've actually gone away from isofix and back to the old method. Mainly due to:

a: The Recaro's being so easy to fit (young Sport)

b: Isofix seats are very heavy in comparison to non isofix, so lifting/fitting them is more strenuous even though the system is more straight forward.

c: No nasty sharp clasps to damage your leather seats.

d: My wife's BMW's isofix anchor points are so deeply sunk they are impossible to locate anyway. RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI