Was on my way home from work today in 5th, then changed into 4th slowing down. Then shortly after the gear stick became very loose and i could only go into 3rd and 4th gear. Now i can only use 3rd and 4th.

Does this sound like the linkages have gone or something worse, also how much is it likely to cost to get it fixed?

one of the linkages yes.
They are under a tenner each. Simple fitting job aswell.
Haynes has a good guide actually.

Thanks alex