vba concatenate with space

[excel01noob]

I have a sheet with data in several columns.
I want to use column A data (month) with colum D data (Product) and column E (billing ID)

How do I concatenate these 3 columns and have the data separated by space?
something like this

March pencil B34009

 

[excel01noob]

Just amazing, 5-stars, Mr. Rothstein!!!!

Finally, on column Q I will have to add all the way down a text such as
"Invoice April 2021"

As it happened in the past, it might be that we are doing the invoice later than the current month.
How do I include in the formula a user form asking user to insert the month and year for the Invoice?