maybe a silly question but if my car is in access height do i need to change it to normal height before driving off or can i just drive off and let it change itself???

You will get a warning flash up on the dash and it will change itself once you exceed 15mph or thereabouts 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

yeah i know it changes itself but is it ok to let it do that or should i change the height myself before driving off

It's not a "bad" thing to let it change itself but by driving at access height for a period of time you potentially increase wear on components. For a start the tyres will be incorrectly aligned (not by much but enough to increase wear if done a lot). 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed