This is my first time trying home brewing and I've started off with a small batch kit of English Ale just to try it out. Everything went well except I got pulled away from the kitchen while wort was cooling and when I got back I noticed the wort had cooled just below 55°C and I wanted to know if by doing so did I just wreck this batch of beer and/or what changes in taste/quality would I possibly expect.
After pitching the original yeast at 55C I think it is fair to say the brew now has "too little yeast". Re-pitch new yeast ASAP. Even if some yeast remains alive, too much yeast will be MUCH better than too little yeast.
If the kit was an extract kit then I might also advise not boiling the extract in water. The extract is already boiled in the factory and the contents arrive in the can already sterile. Just dissolve the extract in boiled water and top up with tap water to the required temp. It can (no pun intended) help prevent such problems and is quicker to do.
It may depend on what yeast it was, but chances are that you have killed the yeast (55°C = 131°F). Some yeast are more tolerant to heat than others, but worst case scenario, if fermentation does not start within 2 days, you can buy a new pack of yeast at your local homebrew shop and pitch it in.
Your beer will probably not have suffered anything by delaying the fermentation. Just make sure to keep it air tight as much as possible, specially if fermentation has not started.