Either will work. A cable would be a good solution if you can run it easily - 30m isn't a problem.
HomePlug/PowerLine are also acceptable if you are unable to run the 30m cable.
Cable will always be faster but HomePlug should be easily fast enough even with a slower speed adaptor.
Chose which is easiest for you. Cable is cheap if you buy it from ebay whereas HomePlug is likely to cost £40-50 as you need a pair.
One advantage of HomePlug is you can easily move the adaptors to different mains sockets so you have a very flexible system. Always plug the adaptor directly into a socker and don't use any form of flying lead.