How can I best use my time as a Mathematical sciences PhD student in the UK I would like some useful advice regarding pursuing a PhD in mathematical sciences in the UK. I've just started my PhD in mathematical modelling and would like to know as much as possible about how to make the most of the entire journey. I have some ideas here and there but I want to know what things to do and things to avoid, planning ahead, useful websites etc. 

Topic/Question have been edited to broaden scope of question.
As a recently-started science PhD student myself, I can recommend:

The Research Student’s Guide To Success
Pat Cryer
Pub Open University Press, 2006
ISBN: 0 335 22117 3