+1 for asking what's the exact problem you're having with your night time shots, although from your original post, it looks like you're having issues when using the zoom.
Looked up the spec of your camera, and yes, at maximum zoom, you are essentially using a "daylight" lens. At f5.6, the aperture is very small for low light work, so you WILL need a tripod. Night time photography either needs very wide aperture lenses (which you haven't got) or long exposures (which can generate good results if you know how). Sometimes both if you're working predominantly with ambient light i.e. no flash, and each has their drawbacks. High ISO is a given, but the higher you go, the grainier your shot. With film though, the grain just adds to the feel of the image.
Throwing large amounts of money at something doesn't necessarily solve the problem if you're not thinking about what you're doing and why. Same is true for just about every aspect of photography tbh.
Bridge cameras have their drawbacks once you start pushing them beyond their limits, but poor technique / poor understanding of theory tends to provide equal frustration. I'd highly recommend getting a GOOD book on photography before you start spending money on kit. Particularly film photography, as they go through the theory much better than the more modern tomes. The 35mm Handbook by Michael Freeman is excellent - they regularly pop up on the 'bay for less than a fiver.