I enjoy teaching mechanics probably the most of the A level modules so am happy to help. If he can work out what the issues are then I can help with more specific advice but for starters:
* draw BIG diagrams using a ruler for straight liines
* mark forces clearly
* set out what you are doing ie state 'resolving horizontally', 'taking moments about A', etc
* note 'trigger' words, such as, inextensible and know what they imply
The FMSP resources are good and used by many schools - also look here:http://www.examsolutions.net/maths-revi ... cation.php
In terms of the student - have a 'trial' lesson before committing yourself - just because someone is good at maths does not mean they can teach it. Yes - there are differences between boards and it is better of the tutor has done further maths as some of the material [and ways of tackling it] are different at uni.
Download the specification from the OCR website - there are loads of past papers.
Good luck - there is time to sort this.