Clutch judder

Hello new to this forum. I've had an 02 for 4 years. It's developed a judder from the clutch from a standstil but only when the engine is hot. Pulling away from traffic lights it makes a kind of groaning noise and lurches forward. I have to be quick pulling the lever back in to avoid stalling it in front of a line of cars!
The engine has done 15 thousand km. I've never touched it apart from oil and filters. I run it on silkolene pro 4 10w40. I use it mainly on the road and don't abuse the clutch.
Sorry to introduce myself with a question but I thought you guys would know what's causing this.
Thanks Iain

Welcome, would guess the obvious.. worn clutch plates or steels ?, not big job to have a look ?