Yorkie's right, for around £100.00 a Bosch could well fit the bill.
I got around forty minutes per charge, and you can do quite a lot in that time. We had lots of grass paths back then, so sometimes I took two bites at the job, not always though!
They're very light, and easily moveable, but there are so many sorts of the same strimmer, you may just as well go to a DIY shop, and hold one for a few minutes!
I've also found that Black and Decker are so much better these days; some of their new range is pretty good, and I've just bought several other rechargeable tools from their long list of products!