Sore and chaffed inner top of my thighs.

I've experienced the same on a couple of occasions and it was due to the following:

1. Saddle too wide - I bought a 2nd hand bike with an after market saddle that was wider than I'd normally have...caused problems after a week or two when I started to put decent miles on it and also when I changed position.

2. Changing my saddle position I.e. moving it too far forward so I'm pushing back a bit and my thighs are rubbing on the wide bit.

In your case I'd simply book a bike fit with a reputable bike fitter in your local area, they should easily be able to sort you out, this particular problem shouldn't be caused by shorts or chamoix cream (or lack of) in my opinion

Have been there, only resolved my issue after a saddle specific bike fit, in my case the saddle was too low and I needed a flatter, less padded saddle. 

Proper cycle clothing. Embrace your inner "lycra lout".

Some lycra and some chamois cream.

If you arent using close fitting/skin tight shorts the bunching etc of the materials between your outer shorts and underwear and skin will cause chafing and pressure points. 

Chamois cream is essentially lubricant for your thighs....not as bad as it sounds. Lots of cycling specific options, generally steer clear of petroleum based lubes like...aquaphor or vaseline as they will cause degredation to your shorts. 

 Should solve your problem.