Ive just bought a set of 14inch 6J Ford alloys to fit my mk3 fiesta. Will i have to use spacers to fit them or should they just go straight on ?

best way to check, try bolting them onto you car and if they fit without hitting anything, you should be fine. only use spacers if you really must and then if you do use the thinest ones possible, if using thick ones also check the lengths of the wheel stubs to make sure you have enough to attach the wheels safely.
cant see why they wouldn't fit though.