Welcome along mate, as dan has said coilovers even on a completely stock car are a very good start.
persoanlly i'd rahther have a slow D series 1.4 that i can sling into any corner than have a mega fast B series that doesn't handle.
coilover wise, you can spend anything from £500 up to £4000 its up to you really and what your budget will allow, alot on here will swear by a good damper and spring setup if the car is not an all out track car.
search button is your frined when it comes to decisions like that.