The obvious upgrade would be to fit a graphics card.
This is the enthusiasts budget choice at the moment:
You should be able to buy one for around £140.
But there are lots of caveats..... Its a double width card and long so you need space on your motherboard. You need a separate feed from the PSU. There is a danger that you will end up with an unbalanced system as the CPU may struggle to keep up. You havnt mentioned which Motherboard you have.
So its up to you. If you like to experiment and can take the £140 hit then go ahead but there is of course an element of risk.
There are plenty of reviews on this site so its worth checking them out as even a modest card will improve on the APU graphics you are using.
Hope this helps.