Nissan Almera Problem

Hope someone can help, was driving to work this morning straight stretch of road 50/60MPH when car started to make strange noises - louder engine noise, sort of bumping noise from engine, less power and smell of burning. No dashboard lights on, engine temp fine. Pulled over checked no smoke from engine, checked tyres fine, pumped brakes and pulled out again no problems for rest of trip. I have a feeling it may be brake related, that the brakes are sticking or something but I have really no idea. Anyone know what could be wrong. Nissan Almera 04 62,000 miles due a service.

I'm not a mechanic but someone I know had similar symptoms in a Ford Ka before christmas - they had to get an AA tow to a garage though - their problem was with their clutch slipping/broken due to worn/streched cable or slipping plate or a failure of the clutch or something like that.
Loss of power, louder engine noise, hot burning smell. However they had driven for a few miles in this state (apart from smell) before it "went" completely.

Oh God that sounds serious and expensive. Managed to book it in the garage for tomorrow morning, hopefully it will keep going til then. Thanks for the info rgfuller.