While you haven't really said how the address list is set up, speculatively:

2000 names/addresses in the Excel file implies only 2000 rows.

In order to specify where the "post code" goes separately from where the address goes on the labels, the two need to be in separate columns (with separate data item labels at the top of each column) in the spread sheet. If they insist on being on the same line, it's likely that both are in the same cell.

Select the column that contains them both, copy and paste into Word.

It should paste as a table.

Convert the table to text (Alt-A, V, B) - (or in Word 2003 you can use the Table menu, but I've never found it in Word 2010) - and use Word's Edit|Replace (Alt-E, E) to put a tab between address and post code. (cleverness may be required)

When you convert the text back into a table (Alt-A, V, X), you should get two columns in the table, with the break where the tab was.

Copy the table and paste back into a copy of the Excel file¹ so that you have two new columns, (1)Address and (2)post code. Put labels on the new columns. Delete the old address+post column.

¹ NEVER make changes to your original, unless you're ABSOLUTELY certain what you're doing is gonna work.

In Word, you'll need to know that you put a tab into either the Find What box or the Replace With box by typing ^t.

The precise way you'd proceed to split the data record would depend on the exact way the address list is set up, but for a US style address in the form:

City, State ZIP

I'd replace all the [space] characters with ^t (a tab) which would result in

City,[tab]State[tab]ZIP

followed by replace all [,^t] by ,[space], to get:

City, State[tab]ZIP

Word 2003, with typical memory, should easily handle 2000 lines of text to make the replacements. It might bomb due to memory limits somewhere around 500 pages (25 lines per page = 12,000 lines) with "dense" replacements, although I've worked lots of global replace tasks in 1200 page docs.

The conversion back and forth between table and text may take a while but that's not really a very large selection to flip back and forth unless memory is very limited.

Once you have separate "labels" on the Address and Post Code, you should be able to set up the label printing fairly easily, in whatever manner you usually prefer.

If you can't figure out a way to replace one specific space without replacing more than one, the table you paste back into Excel may have "too many" columns; but you can "merge columns" in Excel to combine the ones that belong together, as long as they're adjacent.

Of course, other methods already suggested my work better for you, or your data may require something different.

John