We have no idea what "the other post" is, not what the post said. Post a link to it or quote verbatim.
FYI, fault H2O is, as you will have seen from the search you did for yourself, indicating that the machine thinks it is not filling quickly enough.
Is the water tap, the one to which the machine is connected, properly on?
Is there a strainer, probably in the machine end of the filler hose, clear?
Is the filling hose free of links?
There IS a sensor that detects the level. If that has failed or if it's connecting hose is blocked with soap crud, the machine could think it isn't filling quick enough.
Read this for more info. Its one of the first results I got when I searched so you've probably seen it already but, just in case:
http://www.ukwhitegoods.co.uk/forumsphpbb3/hotpoint-fault-codes-h20-and-f01-t91410.html
I also saw this:
http://www.ukwhitegoods.co.uk/forumsphpbb3/hotpoint-fault-codes-h20-and-f01-t91410.html
Dvdhsu, March 2018