After reading up on the subject, it appeared that using any old cleaning agent would not do, as it could damage the sensor. I went off and had a look on ebay for some MAF cleaning products and settled on this one
CRC Air Sensor Clean, it was £9.99 and took around half the can to clean the MAF sensor.
Removing the MAF sensor was actually quite easy, just a case of removing the plastic engine covers, air filter ducting and finally the MAF sensor itself. Two allen head bolts attach the MAF sensor to the intake ducting, and two Torx head screws hole the sensor to the air filter housing. Once these are removed, and providing the electrical connector had been unclipped, the MAF sensor unit just pulls away.
When removed you can see how much grime has built up, and surprisingly for this car, there wasn't much. There was a few small areas of dirt on the sensor but overall not bad. However, now that it was off I might as well give it a clean.
I laid out some paper towels and held the sensor unit in place over the top. I then sprayed the cleaner on liberally. Despite looking fairly clean, the paper towel had quite a lot of dirt on it afterwards.
I let the sensor dry completely and then refitted it. Unfortunately I didn't get a photo of it after the clean, but it did look visually cleaner. Judging by the towel too it was a worthwhile procedure.
If I notice any changes to the running of the car as a result of this clean I will update this post to describe them.