Grab a bin bag and a chair. Fill the bin bag with anything you see that don't immediately think 'if the house was on fire, I'd take this with me'. Tie the top, shove it in the wheelie bin. Do this once a day - don't think too much about it, it doesn't require intense intellectual debate; are you keeping it? No? Bin it then. Do this once a day and then you're 7 bin bags down on stuff by next Monday morning, give it a month and you've removed the equivalent of a room full of stuff.
Have a large, brightly coloured box file. (Brightly coloured so you can see it under a pile of stuff). Every time you touch a bill, bank statement or official document, put it into the boxfile. Immediately.
Put a bin where you stop when you've picked up post. Drop all junk mail, envelopes, additional inserts, etc, everything that doesn't need action, straight into the bin before it gets any further into your house. If you open a bank statement, drop the envelope and junk leaflets from inside into that bin, walk to the boxfile and shove it in. Straight away.
Do you lose your keys/work lanyard? Put a hook/sat shoulder height exactly where you would stop as you come in through the door, out of sight and reach of the letterbox/on the hinged side. Always hang them up as you walk in, no dumping them on a side where they get picked up, forgotten, knocked off or moved whilst your mind is on something else.
Train yourself to come in the door, hang the keys up, take your coat off, kick your shoes off into a useful storage area right where you would take them off anyway - so if somebody mimed the actions back to you, you'd know they were leaving your house in the morning, or somebody copying you would be able to find their way out in the dark.
Keep your changing bag packed and ready to go all the time with everything you need, other than fresh food/milk. Keep your purse in your actual bag at all times, along with cards, etc.
Have a place where you put your phone on to charge. Near the kettle is good, as you'll be able to put it on as you make a drink/bottle and if you forget it, you'll know where to find it quickly.
Once you've cleared out the stuff that is interfering with your ability to think straight (other than the obvious adorable baby and child, they're non negotiable keeping items), it'll make everything else less stressful.
Then you can go to a cupboard and do another bin bag, etc.