Emmie put your post code in here to see if you are in a Universal Credit area
https://ucpostcode.entitledto.co.uk/ucdate
If you are, do not worry, as its only totally new claims that are affected and as yours is not a new claim you should be ok.
Without too much detail, we have been in a UC area since 2017 and my neighbour I was helping was worried they would put him over to UC but his claim was just a re-assessment so its not classed as a new claim so he was ok.
Thanks for best answer and please do not worry it really is good news x