Is "a lot of work" plural

Is this sentence grammatically correct or can be better.I want to refer to more than one work so is this sentnce correct-
A lot of work of mine is pending because of that document.

I have a lot of work pending because of that document.

Can we use much, plenty of there?

‘Much work is pending because of that document,’ is okay.
‘Plenty of work is pending because of that document,’ is possible, but the meaning changes as a result.

Could you tell me the difference please?

Mr. Beeesneees,
Can I say, " I have a lot of pens" or
Should I say, “I have a lot of pen”.
Please clarify me.
Thanks,
Er.S.M.M.Hanifa

While waiting for his reply, I’d suggest that you not use the second sentence. Just because pen is a countable noun and when you use a lot of, you mean more than 1-plural. So, it’s advisable that you use a lot of pens!

‘I have a lot of work pending because of that document.’
‘Much work is pending because of that document,’
‘Plenty of work is pending because of that document,’

I’ve actually had a re-think about the meanings, and don’t think they are so different after all.

Initially, I saw the first example two examples as specifically negative. That is, because of something about that particular document, the person hasn’t been able to complete their work, and it has mounted up.

Thinking about it, I’ve realised that this doesn’t have to be the case. It may be a situation where because of something about one particular document a lot of extra work has been created for the person. This could be a good thing or a bad thing.

The third statement I originally read as definitely positive (I’ve gained lots of work because of the document), but looking at it again I think there are times when that could also be negative.

So the fact that work is mounting up may be positive or negative for all of the sentences.
Sorry.

I have a lot of pens.
I have a pen.

For the reason that Bookaholic has just given!

Mr. Beeesneees,
Could I say?:
(Plenty of)/(Much) work are pending.
A lot of pens are lying on the table.
Please comment.
Thanks.
Er.S.M.M.Hanifa

Plenty of/much work is pending. - work is uncountable. You can’t say one work, two works, etc. unless under very particular circumstances. ‘These two works by the author…’)
A lot of pens are lying on the table - pens is plural.