I apologise if this is in the wrong forum! I was wondering if there was a mod/program out there for the Sims 2 which will allow you to view which packs are required, or have been used, to create a lot?

It should be listed on the page for the download.
You may also need to click on the SP to see what it includes.

As for a program for it I can't think of one.

For lots downloaded elsewhere it's more difficult. In most cases you can install with the Clean Installer, and any missing items will just be missing.

Pay attention to which EP/SPs the creator says they have, and aim to install lots that match with what you have. If it doesn't say, be aware there could be issues. It's a good idea to have at least the last EP/SP the creator have installed, due to compatibility. Make sure you have the proper EP for any special lots that require an EP, such as apartments or dormitories.

If the creator has AL or M&G, you NEED at least one of those because of game engine compatibility, even if the lot doesn't have a single item from one of those EPs.

If you mean what lots you have created, the EP's/SPs required will be what you have installed when creating the lot. There are several different code bases for TS2 (https://hugelunatic.com/?p=397), as long as your latest EP matches one of the same the lots will install and should not crash. Example, if you don't have OFB but install one of the SPs that use the same game engine, the lot should work.

Oops, sorry for the delay, I forgot to subscribe to the thread and didn't realise it had any replies! Thank you all for your help. I've noticed with the Sims 4, they have a software which allows you to extract lots and also show you which packs have been used in each one. I was just wondering if there was something similar for the Sims 2 that shows you which packs have been used to build a lot. I've done a search but can't find anything so far.