I am currently in my final year of a joint honours degree and thinking about applying for a PhD position. Is a PhD full time study - like undergraduate courses?

In most cases PhDs are full time for at least three years (a part time PhD would be at least 6 years). Unlike an undergraduate degree you only get 6 weeks holiday (including bank holidays) per year - many people don't even take all of these.

Yep, if you take holidays your supervisor gets pretty uptight. That's why she doesn't like x-mas, everybody quits working!

OK, most people in my lab work from 9 am to 6 or 7 pm. The working houres are flexible, you can come and go as you like because your work is your own responsibilty. As long as you don't miss lab meetings it doesn't matter and many people go out for a hour of sports inbetween.

It also depends on how your project is going. If its not going anywhere you might be repeating experiments over and over and spending 10 h or mor in the lab per day. If its going well you might leave at 5 every day. Most people come in at the weekend every now and then.