My supervisors are really keen on publications. It is obviously important for RAE and career progression. What is the average number of publications from a science PhD? Are conference presentations important, as the emphasis seems to be on publish +++? Thanks for your advice.

i don't think that such an average can be given - i know someone who produced 24 publications in his PhD (don't ask me how he did it), while another guy only had 3. A lot depends on your research area I guess. As for presentations: they are probably more important for you personally, since you can get a lot of input on your research, while publications are often read by very few people.

The numbers of publications vary from subject to subject. It is perfectly possible to complete a PhD in the UK with no publications to your name (although you would probably expect to get one or two from your work after you have written your thesis). Three is a very respectable number in many subject areas. If you wish to continue in academia conferences are a very good way to get yourself known by possible future employers or collaborators. Giving a presentation will not only help with this, it may also mean you get to go there for free.