i have a plant in my garden which has leaves like a rubarb but it isn"t a rubarb what can it be

Difficult to tell without a pix. a dock?

Sounds more like Burdock the wild sticky bobbles you bring back from a walk!! unless it is tame! like the Rheum , Peltiphylum or gunnera. Good Luck difficult with out a photo

sounds like gunera to me a member of rhubarb family ,i have the giant version just like ruhbarb but with spiky leaves and stems ,there are a number of different varieties but be careful unlike rhubarb its not edible .hope that helps

is it the british native butterbur? it can grow about 18-24" tall and it has a pinky beige flower a bit like bergina [elephants ear] when settled. it isnt edilble either.
can you get a photo ? it is much easier with one.

Hope it's not giant hogweed....