An A level a early before the rest?

How will unis view me if I finish an a level a year early, so do an A2 alongside 3 ASs (thinking of re-doing year 12 with new subjects except one which i turned out to be good at )
How much consideration will they give if for example you miss your AAA offer and get AAB but got an A in the early a level how much diffrence would it make.

Well for one, if you plan on redoing Year 12 you wouldn't have "got an A in the early A level" in a positive way as you'd have got an A at the normal time (ie: after 2 years) and you'd be behind a year due to resitting Year 12, which is less desirable and they would focus more on the fact you were redoing your AS levels rather than the fact you got an A in 1 A level.

If you resit your AS levels then you still need to include your original AS subjects and grades on your UCAS form. This is regardless of whether you obtained an E, A or anything in between including a U grade. Therefore, the unis will know that this is your 2nd shot at your AS levels. Some unis and subjects specifically state that your results must be obtained in the first sitting, so you will need to check on their websites or email them about your situation before applying. Likewise, some universities will only consider results achieved in one sitting (so any offer made would be on the basis of the 3 subjects that you'd be starting in your repeat Year 12 year and they would ignore the other A level grade) so again, you will need to pay close attention to their admissions policies.

All of this very much depends on where you plan to apply and what for - if you want to apply to medicine then forget it, unfortunately, unless you had very serious extenuating circumstances. Likewise, a lot of the top tier of the Russell Group have or have had policies relating to repeat years in the past. Off the top of my head I know that Edinburgh, UCL, Imperial, Durham, Oxford and Cambridge have all certainly had such policies in place over the last 5 years or so, but I am not familiar with their 2016 admissions policies. However, if you're looking at applying for a "normal" subject at a mid range university then it's likely you won't have too much of a problem.

If you had an offer from a university that was happy to consider your earlier A level result then they would make an offer for 2 A level grades rather than 3, assuming the previous A level met their requirements. You would then need to meet their 2 A level grade offer in full to secure your place and if you missed your grades, then you may find that they treat you differently because you've already messed up once (so to speak) or they may make the decision as they would with any "normal" applicant. They will not know this though until they get the grades through from UCAS and know their exact numbers at confirmation, so there's no point asking this in advance.