Whilst driving along the road I heard a loud dull thud then no power through the car what's so ever central locking everything away no dash lights nowt the battery fine as had it tested any ideas please

Well, from the little info and the discription you gave there is a few things you can check.
If the engine is not running and it won't start, then your timing belt is gone. If the engine will run but you have no electrical you shrould check to see if your alternator bracket didn't snap under pressureand come disconnected from the belts. It may be other things but from the info you provided that would be my first guess.