What sort of fish do you have? And you can plant a tank after its established, it just requires a bit more thought if you have digging fish.
Get yourself some pebbles/rocks (depending on the plant size and fish size that are doing the uprooting), put the plant back into the substrate and put the rocks around the base, you can even zip tig a pebble/rock gently to the plant base and bury it under the substrate with the roots....oh and make sure you have a decent substrate depth too, not deep enough and you will have even more trouble keeping the plants rooted.
If the plants dont have a brilliant root system, you can plant them in a different container (doesnt have to be an actual tank) and give them a chance to get a decent root system, then transfer.
I'll try the rock method, thanks for the positive comments t though
It can be done, dont give up hope