The frame is not worth much, and by removing braze-ons, repairing the dent and repainting you'll likely spend more than it's worth. If you only want a cheap job, remove the braze-ons with a hacksaw then a file and some sandpaper, leave the dent (or use some filler on it) then send the frame off for a powdercoat paintjob. All-in cost should be about £40, wheras a full soup-to-nuts refurb by Argos or similiar would be more like £140
The frame is not worth much, and by removing braze-ons, repairing the dent and repainting you'll likely spend more than it's worth. If you only want a cheap job, remove the braze-ons with a hacksaw then a file and some sandpaper, leave the dent (or use some filler on it) then send the frame off for a powdercoat paintjob. All-in cost should be about £40, wheras a full soup-to-nuts refurb by Argos or similiar would be more like £140