
I'm going to get a bit complicated here sorry.
For what you ask for in your opening post I suggest you go for
Newnet Home M (12GB allowance) for the best ISP at that level. IDNet as suggested by Cavillas is possibly fractionally better but a lot more expensive. Above 20GB per month then IDNet or Zen would be the
quality ones to look at. Newnet does of course have 20GB Home S which you may consider.
Now the messy bit.
O2 LLU is available on your exchange. The Standard service is £12.23 per month but is a 12-month minimum term. Keep reading!
The O2 LLU service cannot be compared to the BT-based Newnet connection. A major difference is the non-existence of the BT profiling and inflexible target noise margin systems. A lesser but important one is O2 is unlimited.
12 months Newnet Home M is £210.72.
12 months O2 Standard without an O2 mobile is £146.76
Difference £63.96, so after 9 months of O2 you could buy out the rest if you wanted to leave, and still be cheaper than Newnet at 9 months. At this point the decision depends partly on why you don't want a fixed term, as well as the other factors above.
But it gets more complicated - in favour of O2.
For starters if you sign up through Quidco after following the recommendations about clearing cookies then you get £50 cash-back after 3 months. (Less £5 if it is your first Quidco transaction in a month). So that makes O2 = £96.76 or £101.76 for the year, and the pay-off point is 6 months.
Then, if you have an O2 mobile phone there is a £4.89 per month discount on the broadband. A PAYG phone with £10 per
quarter qualifies.
Still fairly simple, but now ...
On O2 Premium you won't get any higher speeds, but there is an offer on of 3 months free, which you can get as well as the Quidco cash-back.
That makes the first 12 months £132.12 or £82.12 or £87.12. Cheaper than Standard! And of course the mobile phone reduction is also applicable. The draw-back would be at the end of the 12 months a downgrade to Standard would start a new 12-month term. But if you were happy that wouldn't bother you.
So I will leave you to find an envelope and pen to do more arithmetic comparing with the Newnet (or indeed any ISP) costs. The excellent
document by MKD has the full O2 calculations in the last page, and I see that is now accessible by itself.