[Closed] Buying first car tomorrow - what do I need to do?

Hi there,

Looking for a bit of help so proceedings run smoothly and I can drive away the same day.
If I decide to buy it, I have an insurance policy ref number from a reputable company - so presumably sorting that is a case of ringing them up and quoting the ref number and then transferring money across.
The car should already be MOT'd I think (it says it has 12 months MOT on the listing).
With regards to tax though, how can I sort that? Can the dealer do it? Or do I need to ring a number of some sort?

Is there anything else to do?

Any generic advice would be good too!