My headlight bulbs have gone again is there an easy way to change them myself? [450]

No, either you have the skill or you don’t. If you try to change the bulb and accidentally dislodge the spring clip the headlight has to be removed and the front end will have to come off as well to replace it. The headlight will then need realigning too. We would recommend going to a Smart specialist garage who will have experience with this.