Hi kloofneck,
I'm slightly confused, since you just said you're not going to buy this particular car.
Hypothetically though, if it's taxed to Feb '14 then you'd be entitled to drive it right away, in terms of "vehicle RFL is paid", afaic.
With the insurance though, you need to speak to your insurance company about your plans - even though it's only a plan at this stage.
They need to work out what the annual premium on this car would be (and they might not like the car's accident history). If you're on a pay monthly plan, they just adjust your payments. If you've paid up front for the whole year, in advance, they need to calculate whether they want you to pay an additional sum.
Example
Old car premium £300, you paid all £300 but have only used 8 month's of this so far
New car premium £350/year but there's only 4 months to go until annual renewal so you only owe them 4/12ths of the extra £50. At renewal time, you'll pay £350 (give or take the usual annual price hikes).
I hope that makes sense.