a lot / alot / allot
A lot is two words. Alot is not a word. Allot is a verb, and it is not what you meant.
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Wrong: There’s alot of work left.
Right: There’s a lot of work left.
Alot is not a word. You would not write abunch.
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Wrong: There were allot of people there.
Right: There were a lot of people there.
Allot is a verb. Nobody assigned anyone to anything.
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Wrong: We should a lot two hours for this.
Right: We should allot two hours for this.
Here it is the verb. Two Ls, and it takes an object.
The rule
A lot is two words. Always, in every register, with no exceptions. Alot is not in any dictionary because it is not a word.
If you need a test: you would not write abunch, afew, or alittle.
Allot is a real word, just not that one
Allot means to give out a share of something. We allotted three hours. Check your allotted seat. Two Ls, and it needs an object—you allot something to someone.
The two are genuinely related, which is why this feels slipperier than it should. A lot was originally a portion decided by casting lots, which is where lottery comes from too. Allot is that same word with a prefix on the front: to divide by lot.
In fairness
The instinct that it ought to be one word is not stupid. Already, altogether, and always all started as two words and fused. English simply has not done it to a lot yet, and until it does, one word is wrong.
This should help alot.