She wants to become Muslim but she does not know where the qiblah

Praise be to Allah.

Firstly: 

We congratulate you on reaching the right decision and coming to know the true religion. We ask Allaah to help you and increase you in faith, happiness and contentment in this world and in the Hereafter. 

You have to bear witness to the truth, and testify that there is no god except Allaah and that Muhammad is the Messenger of Allaah, in order to enter this great religion. Do not delay that for a single moment, so that you may be recorded with Allaah among the blessed victors. Even if you do not know the direction of the qiblah, enter Islam and ask about the direction of Makkah, for that is the direction of the qiblah. This is something easy to find out in sha Allaah. Even if we assume that you do not find out the direction of the qiblah, try your best to find out which direction is most likely, and pray facing that direction; your prayer will be valid and there will be no sin on you. 

Go to the nearest Islamic Centre and they will help you to learn Islam and will give you the books that you need, in sha Allaah. 

Secondly: 

You can use a compass or some watches or other things that are equipped with a compass, or a map of the world, in order to find out the direction of the qiblah. 

By looking at a map of the world you will see that the direction of the qiblah for those who live in Britain is South-East, so that is the direction you must face. A slight error in direction for those who are far away from Makkah is forgivable.

And Allaah knows best.