Water - you won’t get a ‘deal’ as there will only be one supplier, who that is depends on where you are. The only way to save is to have a meter and use less… you’ll need to contact the company to set up a new account when you move in.
Gas/electric - sadly there’s not many good deals around atm, but some suppliers offer things like sharing £100 between you and a friend who recommends you (we’re with octopus, they do it). When we rented we were moved to a “recommend” (aka crazy priced) supplier so worth checking if you’re renting through an agent.
Internet I’ve had a good deal with EE before. I’m with them on my mobile and got a decent price broadband deal, plus a tonne of free data on my phone contact. Worth shopping around though - try uswitch. If you’ll be working from home, you’ll need a decent speed. We have 2 of us and have 100mbps which has been great with 2 of us on video calls most of the day
Insurance, it’s worth shopping around too- but read the small print! I wouldn’t consider insurance that has a defaqto rating of less than 4/5*.
Also worth finding out about the council tax band for the property so you can budget for that too
