I have started a PhD and am 6 months into it...and have relapsed with depression which has been a problem in the past...i want to take time to sort myself out...can i take a lot of time off/ start going part time/stop and start a new PhD next year? anyone got experience of this?

You should talk to your supervisor about this, as they will probably be in the best position to help you. Without their support it may be difficult to sort things out to your own satisfaction. Have a look at the web site of your grant awarding body and look at their policy on absence due to illness.