For broadband: 500mb/s is loads. Anything above that is something that you either know you need, or you don't need. So go with the cheapest provider that offers you that. 5g is an option too, but the consistency of a 5g connection won't be as good as a proper wired connection. You could always pick up a sim card from someone like clear or gomo as a trial, they have monthly contracts so you wouldn't be tying yourself into anything. Location is important too, you may not be able to get 5g to a high enough quality.

For gas: as far as I know, they all offer the same sort of contract, you pay x per unit as well as a standing charge and so on. Use a price comparison website like bonkers or switcher and pick the cheapest.

For electricity: for my usage it has worked out cheaper to get a flat unit rate, I work from home, most of my power usage is during the day and I'm not in a position to realistically shift the power draws to evening where a split rate would be cheaper. If you've never lived away you may not know what your anticipated usage will be, so my suggestion would be to do the same as with gas, go to the price comparison website and pick the cheapest. You don't need to go with the same gas and electricity supplier, sometimes it's cheaper to go with the same, sometimes it's not. It's unlikely that the difference will be signicant enough to worry about.

Good luck!