Best speak to an accountant on this. Like Solicitors, many offer a free initial consultation. You will need to become self employed and register for VAT. Some of my business associates have claimed back the vat on PPL (H) training and left it to their accountants to sort it out, then justify it with the VAT people. Also talk to your local training and enterprise council and find out about a free bookkeeping and business advice course.
Whirlybird may be a good person to advise here as she was self employed before starting her PPL training. PM her.
Mike