There used to be a gold exploit at the inn. But I simply cant remember how it worked? Help?

Inn & Toughen exploits won't work in the GOG version, as it has a more recent patch. Same with quickly swapping quest items around to keep them. The best exploit for gold with the current patch is to get the Fletchery skill on a ranger, equip a bow, and have them duplicate their equipped arrows. Enchanting the arrows (especially Dragon Arrow) with +to Hit makes them extremely valuable, and selling copies of them can add up very quickly.

An earlier-accessed gold trick is to join a guild. Buy a stackable item, from the special Guild shop, such as ammunition (bolts in first town's smithy). Sell them back to the shop for a profit. This is especially effective with a Merchant-traited character. You can buy more and more to inflate your amount more quickly.

However, if you have a base version of the game, you can follow the instructions below for the Inn glitch.
-Save first outside town in case of issue.
-Pool gold on (#1) PC.
-Remove all PCs.
-Create a character (#2) & add to party.
-Add #1 to party.
-Pool gold to #2.
-Remove #1 from party.

--When #2 has a lot of cash, add #1, pool to #2, pool back to #1, delete #2, leave, then repeat the steps. With the large amount of cash, the money will inflate a lot faster.

When you have enough money from any source:
Make sure you keep your large amount of money either in the bank, or in your back PC's pockets (checking after fighting any rogue/thieving-type enemies - good to keep quest items here too).

Also, if you have an unpatched/CD version of the game, and want to switch between versions to use the glitches, there are some instructions on page 22 of the thread below:
http://www.ironworksforum.com/forum/showthread.php?t=29026&page=22

Is it possible to get an UNpatched version of W&W from Gog? Or failing that to remove the patch?

Gog only supplies the patched version. You would need the original CD version to downgrade (or use and then transfer saves to Gog's version later).

However, the alternate methods (other than Inn) above can be used even with Gog's patched version. You can still get the massive amounts of gold. Or, for even faster wealth, you could use Jeff Ludwig's editor to change a commonly dropped item (arrows) to be worth a ton of gold each.

Where would I find this editor?

Link to info: http://www.jeffludwig.com/wizardswarriors/editor-basics.php
Direct to download page: http://www.jeffludwig.com/wizardswarriors/download.php

It also allows changes to specific monster tables & drops, allowing for some more possibilities.