If you're heading from the Crouch down the Roach then you need to check tides but 1m draft isn't a whole lot but you'll want to be reasonably up on the tide. And you have Havengore Bridge to get through that has limited opening and obviously won't let you out if the MOD are in operation there.. (I'm assuming that's still going on)... Pick your tide and you should be fine. 1m is very similar to my old bilge-keel saily boat so my opinion (not technical advice of course ) it's quite doable if you plan it..
Ring the bridge on 01702 383436 to check opening times and that it is working
Call on approach Ch 72 "Shoe Bridge"
You'll be alright with that draft but I'd choose a good tide and get there a bit before HW.
Havengore is a great shortcut to the Thames from the Crouch/Roach but you really need to be transiting the bridge at, or just before, HW and on a spring tide. I've been through loads of times, but even at optimum timings the depth below the boat gets very skinny. Bridge only operates for boat traffic at weekends (officially its when the range is inactive, but this only seems to happen at weekends or occasionally, if you are lucky, on a Friday afternoon).
Assuming your trip only involves a day out to the "Thames" need to take into account any day return will be via the Whitaker Bouy.?
If heading upstream to the London marinas, boat will be punching the ebb all way and unlikely to get into any marinas due to lack of water.
Any trip to Teddington requires to be at the lower end of Sea Reach around LW.