Virgin Buckfast Queen

There are 2 main factors that will determine which one to go for. Price and timing. Virgin queens will be cheaper than a Mated queen but they do have a higher risk of failure as they need to go on their mating flights which may not work out. This also means that it will be around 2-3 weeks before you see eggs appearing in your hive. A Mated queen should start laying within the week.

So you've brought a new queen - what to do?

The first step you need to do is make sure the colony has been queenless for at least 48hrs ideally. If you are replacing a Queen because is is failing, then you need to find her and remove her from the hive before you add a queen. If you are not sure what happened to your queen - she has just 'vanished', then you need to make sure they definitely need a new queen and that they don't have a virgin queen running around inside. If you do have one in there, they will not accept this new queen when you try to put her in. It is also important that you remove any queen cells that they make after you make them queenless too.
One good way to test if your colony really is queenless is to add a frame of eggs to the colony and see how they react to it.    If they start making queen cells, then that is a sign that they are queenless as they are naturally trying to raise their own.    You can safely introduce a new queen with what should be a high success rate.     If, however, they do not attempt to make any queen cells, then the chances are they have a queen in there somewhere but either it is a virgin queen, or it just hasn't started laying yet.   Either way, normally leaving them a week or so should show better or clearer results for you.

Getting Your Queen.
The new queen will come in a cage and you can use this cage to introduce your queen into your hive. The cages will all vary in size, shape and colour but the principle is the same.
Put the cage into your queenless hive, between 2 frames of brood (if they have any), otherwise between the main cluster of bees. Leave it in there for around 2 days. Don't worry about removing the attendant workers that come with her. They will die, but their sole purpose is to make sure the queen is looked after until she is in the hive. Leaving them in there makes no difference to the acceptance of the Queen either.
Also, do NOT remove the plastic tab that is covering the candy plug yet.
After around 2-3 days go back and then remove the plastic tab that is covering the candy end. Put the cage back into hive. This has allowed the bees in the hive to get used to her but now you are allowing them to slowly gain access to her. They should eat their way through the candy within a couple of days.
Optional step: after about 3 days, you can go back and remove the cage, making sure that the queen has been released from the cage. Sometimes, she can get trapped in there but you should be safe to remove her manually by now (be careful she doesn't fly out of the cage though). DO NOT BE TEMPTED TO CHECK THE HIVE - doing so may cause the bees to stress out and kill the new queen.
We suggest you leave the hive alone for at least a week, ideally 2 weeks. But after that time, you should fine there are a frame or 2 of eggs.

Other Info
Queen introduction is never 100% successful.  However, there are a few factors will help maximise the success rate:
1 - leaving the colony queenless for longer - We say leave them 24-48 hrs queenless before adding a new queen but leaving them 5-7 days will increase the success.
2 - introduce into a small colony - introducting into a smaller colony such as a nuc is more successful than trying to add a queen into a full size hive.   If you do need to add to a big colony, try making a 'split' or 'nuc' from the hive, say 2 or 3 frames of bees, leave them queenless ( see above) and then adding the queen into that split.   Once successfully introduced, you can then merge the colonies back together again.

If a colony of bees is queenless for long enough and they have no brood of any sort left in the hive, then workers can start to lay eggs in the cells themselves. These are unfertilised eggs so will not be of any use for the colony. Unfortunately, by the time you get to that stage in a colony, it really is not worth trying to safe them. The remaining bees will very rarely accept a new queen being introduced into the hive, they will instantly kill her. The best method is to move the hive off the stand and then shake out all the bees from the frames and let them drift into your other nearby hives. You can then clean up the frames and hive and repopulate it with a new swarm, a split from another hive, or purchase a nuc of bees.
A colony with laying workers often has multiple eggs per cell, rather than the usual one.

However, don't be fooled! a newly mated queen, with all her excitement and vigour can also lay multiple eggs per cell when she first starts off. however, she will soon calm down and find her proper laying pattern soon enough.
laying workers will also produce a very irregular pattern with 'drones' being laid in the smaller worker cells.

Yes, definitely mated so don't worry about that. However, because the queen would have been placed in the queen introduction cage the day before you get her, she may not have been fed so much as usual as if she had been in the hive. This causes her to shrink in size. Don't worry, introduce her as recommended and once she is out and laying, you will find her size increases back to normal.