For loans and/or grants you will need to get those from the US as UK student loans are only available to UK students. I believe that you can apply for Stafford and/or Sallie Mae loans? (hopefully someone else can confirm that) - that is what previous international students from the US have applied for in the past.
I don't know much about being an international student.
Ok, so a basic rundown is:
1) Decide what subject/course area you want to study (you will need to apply for a specific course at each university you apply to - as an example, in 2000, I applied to study Physics with North American Study at Exeter, Physics at Oxford, Physics with Space Physics at Birmingham and Physics with Astrophysics at Southampton.
2) Look around at some UK university websites to see what courses they offer (the UCAS site has a good database of subjects/universities) and contact the universities you are interested in to find out what you need to do to apply and whether or not you meet the criteria for the course.
3) For an undergraduate degree, you may have to apply through the UCAS system (although because you are not a UK student you might be okay to apply directly to the university). UCAS admission deadlines for starting a course in Fall 2010 are October 15th 2009 for Oxford/Cambridge university, Medicine, Dentistry and Veterinary Science and January 15th 2010 for all other subjects (deadlines for a Fall 2009 start were October 15th 2008 and January 15th 2009). If you are able to apply directly through each university, they may have different deadlines.
4) Once you have been accepted onto a programme and have decided where to study (and have received the relevant documentation), you can start preparing for a student visa application. You can enter the UK up to 1 month before the start date of the course and you can apply for a student visa up to 3 months before the date you wish to enter the UK (so a maximum of 4 months before the course begins).
5) In order to apply for a student visa, you need to show that you have 1 year's worth of tuition (about £10,000 for international students) plus living costs for 9 months (£5,400 if you will be outside of London, £7,200 if you will be studying in London) available to you before the visa will be granted. Although you are allowed to work up to 20 hours per week during term-time and full-time during the vacations, you have to show that you have enough money to cover tuition and living costs without having to get a job while you are in the UK.