Dh and I are both on tesco, pay monthly but not contracted, dh is £12.50 (think it's going up 20 p or so though) for 2gb a month internet data, 800 mins and unlimited texts, my plan is old and I'm not sure they do it anymore but I pay £15 for unlimited calls, texts and internet.
Dh used to be on same plan as me but reduced, salesman said he shouldn't because nobody offers unlimited internet at that price without a minimum length contract and he thinks we got it in error because he could not find the plan on the system. When I was trying to switch DHs plan he almost called me a liar when I said our existing ones benefits, because he was convinced I must be on a 18 month contract and not a rolling monthly one!
Bil switched to Tesco too as he was paying double with O2 (tesco use O2s lines or whatever so signal etc is the same) for the same stuff, mil is on a £7.50 plan but I can't remember her benefits.
I like that if I can't afford I can cancel without penalty, that is can log in and change caps, you can have a higher cap set for abroad if needed, although tesco won't be charging extra for roaming anymore, you can also see fully itemised calls,texts and internet usage etc, so if your dd use her limit up quickly you can see exactly where.
I have a £2 cap because some 0845 numbers are not included in the plan and until recently my GP used one of these numbers, and I'd be charged for tax credit calls until I learned to look for the "are you calling from abroad?" number on most websites as phoning that number is in plan :)