A very mild bleach solution is the cheapest way. Test a bit of your awning first to make sure you got the solution weak.
OR you can use just normal household bathroom cleaners which have 'mould' cleaning qualities. Again just test a bit. There are proper caravan one's but they are dear and often the same as bathroom cleaners.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.