You can just tell the firm you no longer want to go ahead. However, if you may need it further down the line I would think long and hard about it as you will have to start all over again.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
You sound as though you feel that, at some point in time, you will be unable to afford the loan repayments --- if this is inevitable it would be wise to make your arrangements now, while you have some time. Hopefully, however, your situation will hold or even improve.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk