Would anyone be able to give me a rough idea on how much it would cost to have the exterior of a 2005 RRS updated to 2012 Autobiography spec?

Have a look in my gallery - is this what your after ?  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

I'd consider selling your car and buying one already converted. The cost will be a fortune if done right. There are quite a few that have done it now including Peachy which is a very good example.
Another example here and how much this guy has put into it. http://www.rrsport.co.uk/forum/topic34486.html

Thanks Ady - proper job with brand new genuine parts - £5k to £6k budget needed - then £300 reversing camera & GVIF to have what the 10MY has as standard. Throw in freeview - new napa steering wheel - Blackvue - lowering tool for suspension - side steps - another £1k. That's without genuine rubber & carpet mats - rubber boot mat £300.
I have seriously considered purchasing a 12MY but to buy a car for £500 a month for the next 3 years with exactly the same exterior as mine & gain a warranty - £1600 for 2 years - & newer interior - ( which mine is immaculate & I've recently priced up new AB Skins to fit mine £1k fitted ) All I have then is the same looking car - don't get me wrong I'd love nothing more than a SDV6 - Orkney Grey AB fully loaded Sport but its a bridge to far at the moment so I just pretend  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

I haven't actually bought one yet. Obviously if I find a car exactly how I want it then this would be perfect. I was just wondering what the costs would be for me to buy one and then have it upgraded.

I'd love to check your gallery PEACHY but each page takes 15 minutes to load on this site out here for some reason, it is only this site?!

In my opinion the Sport looks good in most forms be it 2005 or 2014 ( except the pink versions ). I work & see them every day so I've watched them evolve but I got the bug early on & it's been a holy grail to upgrade ever since. If I am really honest I've enjoyed every minute & I've met some cracking people & learned such a lot. ( most from on this great forum )
What would I do if I could start again absolutely nothing different  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

when looking to buy my car i saw a few which didn't have genuine land rover parts and they looked to be honest.

Simple things like panels not lining up properly, it just made the car feel unloved.

Defo go with genuine parts!