Nottingham is amazing. I've had beers fermented a smidge too warm turn out fine with it. Perhaps not jaw-dropping, but definitely good.
The beer that you're brewing now is going to do what it does unless you do something like put it in a water bath.
I recommend taking all this awesome energy and excitement you have for getting an accurate temp reading and put it in a simple water bath.
Then by some plywood, two by fours, cheap foam insulation, gap filler and a cheap dorm fridge and making your own fermentation chamber. Can't recommend that enough. I did it on a day off. The best day off I ever spent not brewing.
If you're not trying to enter a competition, fermenting a little higher (read: don't ferment at 80+ degrees) is not going to hurt anything. You're always going to end up with beer in the end.
I'm working on a temperature controlled fermentation fridge as my next step in homebrewing, but I make beers with Notty yeast all the time and it ferments at a sticker-thermometer temp of 73 (probably 76-78 in the wort). Beer tastes great and everyone loves coming to my house to drink my new brew.
There's some info here that needs correction. It may be encouraging, but it's not really helpful to the OP or to other newer brewers reading this thread to tell you it's fine to pitch or ferment at temps that are too warm when it's something to be avoided if possible. There's a world of flavor difference between an ale that was pitched and fermented in the mid-60's vs. the same recipe done 10 degrees warmer, especially with a more temperature-sensitive strain like Nottingham.
Nottingham is my go-to dry yeast for many beers and is excellent IF fermented on the cool side of things. It's also the best ale yeast for making ciders. It'll successfully ferment in the upper 50's (I've used it as low as 55*F) to produce a very clean flavor. But, the "never exceed" temp during active fermentation for Notty is 68*F. Anything above that and it has the tendency to kick off some yucky-tasting esters. I've tasted a friend's brew that used this yeast at 72*F and poured the rest of the bottle in the sink. Then I helped him set up a fermenter fridge.
Agree on avoiding pitching too warm if possible - just saying its not the end of the world unless you pitch in wort that is still hot and kill your yeast (did this once before because I was too impatient).
I was curious about the first response regarding the temperature strip not being accurate. Everything I have read from people who have claimed to directly compare the strip reading to either a thermowell or a direct measurement of the liquid in the fermenter has indicated they are quite accurate, usually +/- 1 degree F.
I am curious enough to try some measurements and will come back and eat some crow if I find differently.
Mid-60's is an acceptable pitch temp for most ale yeast. It's a really good idea to verify that with a digital thermometer (which is one of the basic brew tools anyway). Some decent ones can be had on Amazon for about $15.