I am with 3. - After getting a 65 quid bill, I have set my credit to Zero.
I now pay 5 quid per month extra for broadband ( only on my phone )
I looked at your spec. I see you have wi-fi so you can log into any wireless internet that is not password protected. Or a friend willing to share their code. This will be free of charge.
Be careful, it's easy to run up a bill if you're new to that sort of thing.
Jim