Dynamic nth Day of Weekday-Next Month

I am having some trouble getting this to be reliable. I am using the following formula:

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I would like to be able to type in a number such as 4 so that the formula will return the 4th weekday of the next month.

How can I do this? I would also like to be able to type in a time in another cell that will be included in this formula, if possible

Any help would be appreciated.
Thanks in advance.

By 4th weekday you mean the 4th Monday-Friday day, i.e. 4th weekday of next Month (July 2010) will be Tuesday 6th?

Put 4 in A1 and use this formula in C1

=WORKDAY(EOMONTH(TODAY(),0),A1)

if you want a time added put the time in B1 in time format e.g. 14:00 or 2:00 PM and just add it to the above in C1

=WORKDAY(EOMONTH(TODAY(),0),A1)+B1

format C1 in required date/time format