The main part of your trip is the job you will find. Do not forget that English bosses don't know "les 35 heures". If you will work 35 hours, it is thanks to your UCL day! If you are going to work with a cool staff, entertainment will also be related to your job.
So the first advice I can give you is this one: "Do your best to find the best job" !
Consequently, the first page of the sectiondeals with the job quest. In the second part, you will find several tips about money matters.