Really, the answer to this question depends entirely on what you are willing to spend. If your budget is low, then I would suggest a Line 6 UX1, as that comes bundled with POD Farm, which is a decent piece of starting amp modelling software. You could also possibly get the PreSonus AudioBox USB (can personally recommend that, fantastic little interface and also has 48V Phantom Power in case you ever need to record with a condenser mic or use a DI box) and if you're lucky and they're still doing the bundle, you could get some good software and a good large diaphragm condenser.
In any case, emulated line outs are never really a good idea for recording, you'll be surprised at the tone you can get if you buy a decent interface and use some amp modelling software (such as PodFarm, Revalver, Guitar Rig, Amplitube, whatever takes your fancy). In general, you'd be much better off plugging your guitar straight into the interface and using software on your laptop than using the line out on your MG30.
Either way, once you get started into the world of recording, the world is your oyster to try out any ideas that come to mind, whether that's using the mic jack on your laptop, spending £100's on a complete recording solution or messing around with software amps, you literally can do and try anything!