You could start by contacting banks and getting information about loans and mortgages. Your student might also have materials that (s)he can bring in.
The letters and pamphlets you receive can form the basis of your teaching materials. You can use them for reading practice by designing your own activities to go with them. Remember to include warmers, to pre-teach necessary vocabulary. Then move on to reading for gist and reading for specific information. Follow it up with a related activity.
You can follow this up in later lessons with a cloze test. For this, you blank out certain words in the text and the student fills in the blanks. You can also re-type the materials (check the copyright laws on this) and jumble the sentences, or jumble the words within sentences. Your student can put them in the correct order.
You could record an interview between yourself and a willing colleague with one of you asking for a loan or mortgage. This can be used for listening practice. Design activities on the same format as above for reading. You can also use the recording to present and practise questions as your student will probably need some work on this. You will probably need to do extra work on “how much” and “how long”: “how much do you earn / do you need to borrow?” and “how long have you had your job / have you been in your current home / do you want to take for repayment?”
Large numbers should also be focussed on. You can do a number dictation. Start with you dictating and the student writing down the numbers; then have the student dictate while you write. The language of advice and suggestions might also be useful. For example: “I recommend you repay over 25 years”, “You could take out X mortgage” “X mortgage might be better”.
You could also do an interview between yourself and the student with you requesting a loan or mortgage. It would be a good idea to do this at the beginning of the course for you to see which areas need working on. You could then repeat the activity at the end of the course to evaluate progress.