Typical hourly rate for extra private tuition at upper school level?

A typical rate for private tuition at almost any level is between £25.00 and £30.00 per hour. You can ask for travel expenses if you wish but, unless they are very high, I wouldn't bother - it looks a bit greedy - but there's no point in being out of pocket if expenses are high. Also charge for any other expenses. eg. stationary, photo-copying, work books, etc. But, whatever your charges, make sure they are fully understood along with cancellation payments should you be cancelled at short notice.

I am writing this assuming you are a potential tutor but if you are a potential "client" then the information could be useful.

It depends where in the country you live, what your qualifications are, whether you have to travel to the student's house or they come to you, whether you get paid if they cancel for any reason, etc, etc.