I'm a PhD student in experimental biology in the UK. My funding grants me a monthly stipend for 3.5 years (including money for consumables/conferences etc).
In my group, the standard practice is for people to work for 3.5 years and then write up (though actually different people have different funding, and the funding that the department provides directly does last 4 years).
When I started, I was quite happy to stay for 4 years (the stipend is sufficiently generous that I've saved enough to cover me), but, relationships with my PI have deteriorated significantly. * At this stage, I've said that I wish to write up at the end of 3 years, and be ready to viva by 3.5. This is something that she refuses to grant.
What should I do in this situation? I don't feel that anyone can be expected to work for free (theres no expectation that I should have saved money), and therefore feel that (1) she should either give me her blessing to write up, and all the support that goes with it, or (2) she should find additional funding for the final 0.5 years in order to force me to write up in the department.
Note: the UK has a different funding model to the US, and I'd prefer to just hear answers relating to the UK funding situation (i'm well aware that students in the US have a far tougher time of things, both in terms of money, but also in terms of the very very long PhD's that some people must endure).
*: We've had a difficult relationship from the start, truthfully. She is fairly old and established at this stage, and has very little interest in discussing things, but rather dictates her wishes via emails from her secretary and then comes to the lab to complain when things don't work. This has slowed my work appreciably as we're constantly jumping around to keep her happy.