above post is right, but I would just add the following... Get the finances sorted as best you can, get the girlfriend and folks in check BEFORE you start studying. You really need as little distraction as possible!!
As for your dad saying you are not rich enough to fly, tell him that you want to make sure that your son may have every opportunity possible, ans this is a way of doing it. Hold back the rent money and give him a £300 bonus when you start work and tell him that that is for all his support.
Maths?? well I have mental shut down over maths and having just found out that working out a reciprical by 200-20 and not -180 has put a smile on my face.
Good luck