I have a petrol grass trimmer - FPGTP25, bought in a winter sale from B&Q last yr, Oct/Nov time, I think I paid £70 for it. It's worth waiting for the sales if you can.
Fab piece of kit, I use it on the allotment to keep down weeds and trim the grass paths. Light weight and has a detachable head, I'm told you can purchase different heads for it, for instance a hedge trimmer attachment for reaching up high but not seen any of the attachments in store.
You'll also need to purchase, goggles, petrol, oil, funnel and mixing bottle. B&Q do a starter kit, excluding the petrol, at approx £10.
For the record, I don't work for B&Q .
all depends on what you want to strim if just light strimming then yes like zoomer44 said b&q have good gear but if you want to do heavy strimming try amazon have whole range of strimmer/brush cutters