For most UK residents this option the electric powered strimmer is going to be the weapon of choice. They are relatively cheap to buy, very robust , lasting many years. You don’t have to charge them up or risk the battery being damaged over winter in the very cold temperatures. The weight is about optimum too as the power source is not having to be carried around. So ideal for the older gardener where fatigue using a petrol or any heavy equipment plays a part.
The cable is not at such risk as with the electric lawn mowers, as the cutter on most of the strimmers is just a plastic cord, much less likely to cut into the insulation.
The only drawback is having to use power cables in the garden, which can be quite a long job. Fitting an outside socket certainly helps and prevents cables getting shut in doors.
Make sure you check all cables used and replace them if at all unsure about safety. YOU ONLY GET ONE CHANCE !
Make certain you have an earth leakage detector type circuit breaker, they are cheap and will save you if there is an accident with the cable.