At the moment I use Spotify and update it once a week for new music to and from work. Looking to cut costs and save money are their any free (or cheep) podcasts which I could download weekly/daily to get a range of chart/pop/rock music to play on my iphone. My journey is about 30mins each way.

many thanks

One simple option would be to find an internet radio station playing the sort of music you like and then use one of the many tools for recording or saving this direct to mp3. Some of these can be scheduled so you could have a new file or set of files waiting for you each morning.

Sounds a good idea, can you recommend a recording app.

Audacity
http://audacity.sourceforge.net/

This there anything that will work just using my iPhone, I don't really want to have to turn on my computer each day.