As above, depends on what you want to do and how. Machine polishing delivers the best results but requires good equipment (polisher, pads, polishes) and environment (lighting, dust-free, etc). Hand polishing has some good results but requires far more effort. To be adequately done it can take several hours.
You can also achieve different levels of polishing - light swirl removal (can be done by hand) all the way to full paint correction (requires machine, knowledge and experience). With hand polishing, you are limited to a specific outcome and it won't be as good as machine polishing.
Autoglym SRP is a good starting point. Use pea sized amounts and work over small sections, using various overlapping passes eg up-down several times and then side-side. Might be best to plan in advance how to tackle this. SRP has fillers and abrasives which will help reduce light swirls.
You need to clay and polish only two or three times a year. The dodo juice spin doctor can be bought for around £100. Also consider the kestrel DA6 and megs g220.
