I'm currently using an old iPhone 3gs to play music which works fine with the lead, but it won't charge at the same time.
What iPhone or iPod models will charge at the same time? Or is there an updated lead that will work with other models?

Not sure what model year your car is, but I used a lead with an iPod plug on one end, and two connectors on the other end, one USB and one aux plug so it charges at the same time.

I bought this lead,
http://www.ebay.co.uk/itm/LANDROVER-DISC-4..._991wt_962
This was a link to a genuine landrover connector ( I think it may be dead now), I use it to play music from my Itouch,, it also charges it, also works with the ipod classic.
You may be able to find another using the description in the add 2010 RRS, TDV8
bali Blue / colour coded
side steps / flappy paddles
black perforated leather
22" overfinch
heated everything, TV,fridge ...... now with gold calipers and mud flaps !( black mud flaps that is) !!
Many years ago,,,,, 1955 series 1 landie , sometimes wish I had kept it

I have the LR iPod lead with a Lightning connector converter. It charged my old iPhone 5 and my current iPhone 6s without issues (thought not the fastest ever charge if heavily using the device at the same time, like for music, Bluetooth and Google Maps. L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso
RRS TDV6 HSE Lux (MY2011)... Nara Bronze / Arabica - now gone!

Thanks for the replies, I have tried an adapter, albeit a cheap one and it wouldn't charge my iPhone. Might have to try a genuine adapter or a new lead then.a