I have lawns front and back. Roughly 5x5m, and 6x8m. Although a bigger one would have helped, I've managed for years with a Flymo 'hover' mower thingy with about a 12" cut. Takes maybe a couple of hours in total to do front and back, from getting the machines out to putting them back.
I formerly didn't mind this at all as I'm retired and time is not an issue. The exercise is 'a good thing'. This may not be right for the OP, but at least gives a reference point to start from. I'd suggest something similar, possibly cordless and maybe with a wider cut.
I bought an electric strimmer, which 'flips' through 90 degrees from horizontal strimming, to vertical edge trimming. This is an absolute God send and makes keeping border edges tidy, a piece of cake.
Above said, were I younger, I'd be thinking of battery stuff which uses the same battery. I have a few tools from the Ryobi One+ range which prove the concept.
Sadly, I'm very close to having to get a gardener in, as the state of my knees means that even getting the machines out is a trial, and cutting the grass wipes me out.
Fortunately a former neighbour and her partner will cut grass front and back for a tenner. Takes them about 30 minutes.
I'd also suggest that depending on soil and climate, a powered lawn raker is a good investment. It takes an hour or so once or twice a year to rake out all the moss and thatch from the grass, which will result in a much healthier lawn. Of course it can be done manually, but it is back breaking.
Also, don't forget feeding and weeding. Liquid and solid products are available.