im looking at a RRS in a few days ,its a 05 111,000 on the clock FSH .

any tips on what to look out for ?

Pretty much everything.... as with any 14 year old car.

But there is the added complexity of the RRS to factor in.

There are a lot of very useful posts on this site which it would be worth your while spending an hour or two skimming through, especially General, Technical and Tips and Tricks section.

On a good day nothing beats them. On a bad day... you will need a lot of patience and deep pockets.

Check cam belts have been done and also check previous mot history online. If it’s had an advisory for brake pipes then that can be an expensive job (body off to get to rears). Also check air suspension works ok  Range Rover Sport HSE DYnamic SDV6 Velocity blue 2020 MY
Range Rover sport HSE Dynamic P400e Silver
Range Rover Sport 3.0 SDV6 HSE Dynamic 2016 MY
Range Rover sport 3.6tdv8HSE 2007 Gone
Range Rover sport 2.7tdv6SE 2005 Gone
Range Rover sport 2.7tdv6SE 2007 honey
Range rover Vogue 2005 4.4 - GONE and missed
BMW 535d M sport 2006 - GONE not as missed
BMW X5 4.4 2004 sport - GONE

I had mine changed with the body on and it was done in 2 hours and cost £400 with a full service at a local LR indie. 2012 5.0 SC AB
Mods:
TPMS
Genuine LR DRLs
Remote Boot close from key fob
2016 Discovery 4 Mirrors AKA RRS2
2014 L405 Surround Camera retro fit (WIP)
2013 RRS Dual View Screen fit (Complete)
2016 LR4 RSE
2014 LR4 Homelink
2016 FFRR Electrochromatic Wing Mirror Glass

70 plate Focus ST (Current)
1942 VEP Ford GPW Jeep (Willys) (Current)
1943 Whites M16 Halftrack (Current)
16 plate Eurofighter Typhoon, 2 x Eurojet engines with 20,000lbs thrust each. 1380mph