Clearing - If you've just missed out on your conditional offer don't worry, call both universities and see what they say.
I would advise you to write four or five bullet points down which you can refer back to when you're on the phone. Important selling points to consider are:
Why would you be perfect for the university? What can you bring to the course? Why was this University your first (or second) choice?
What relevant work experience do you have in relation to your degree?
What is your employment history?
What sporting achievements, music talents or extra curricular attainments do you have?
Prepare well and make sure you put yourself in the best possibile light.
This year, compared to 2012, University application are up by around 2.5%. Although still down by around 7.5% from 2011, so you'll still have a better chance of getting in.
Go onto the UCAS website, click clearing, type in your degree choice and have a look at what is on offer. I would consider joint honors degrees if you haven't already, as grade/point requirements are usually lower. You must make sure you do this on A-Level results day, August 15 2013. I wouldn't advise you to email regarding clearing courses. Phones will be manic, so be patient. I know it's easier to email, but trust me, you must call them.
Hire a tutor or start a short retake course - This is probably the best choice. Companies now offer tailored tuition focusing on sitting exams, improving grades and gaining confidence. I would suggest at least 40 hours private tuition before your exams, perhaps even book block sessions every week. Make sure tutors are CRB checked and have tutoring experience. Ask for a deal or discount. Tutors are financially a better choice and they are far more flexible, a retake college can cost up to £20,000 a year.
A big set back this year, you can't re-sit your A-Level exams in January 2014, June only.
On-line distance courses (Moocs) - There are certainly pros and cons with this options. The list of positives include; it's cheap, (University is £9,000 a year in tuition fees alone) often free, you can study at home in your own time, there are no travel costs, it's interactive and often students start discussions and forums. However, a staggering 90% of students don't complete courses according to the Economist, there is really no help or guidance and you will still have to sit the exams (if applicable) as coursework. On the plus side the Open University has been going, very successfully, since 1971.
Apprenticeships or Internships - these are becoming more and more popular, the government is backing them as are big corporate companies. Have a look at London Apprenticeship - they have a large array of options. Search online for opportunities, get your CV posted and build your LinkedIn.
Best of luck.