Q: Clutch sticking and gears won't go in

This morning the car started as normal and was fine. 5 minutes down the road the clutch began sticking to the floor and I couldn't get the car into gear, it slipped into 4th so I pulled into a side street and stopped-the car cut out then because it wouldn't come out of gear and I was stopping in 4th. I left it for a few minutes, restarted and the gears felt looser then. Clutch stuck to the floor once or twice but then it went fine and I was able to use as normal. Car feels a bit slower and sluggish. My dad used the car yesterday and said the same thing happened while he was doing a 3 point turn-the gears jammed and he couldn't move. Then it suddenly worked again and no problems.

I need the car a lot for work and as I have to travel through the Mersey tunnels daily I'm worried it's going to happen there and I'll freak out. Should I put the car in garage straight away? It seems it's only happening the first 5-10mins of using the car but is this likely to increase?

thanks Karen
My car has a manual transmission.