am I allowed to travel outside of Thailand whilst my Retirement Stamp is under Consideration

Never heard of Non O for retirement needing under consideration delay. 

Yes. As long as you get re-entry permit & back before date on stamp. Had to do it a few years ago

 

Retirement visa only takes a short time, less than 1 hour unless you mean the marriage visa.

20 minutes ago, kelboy said:

Retirement visa only takes a short time, less than 1 hour unless you mean the marriage visa.

He means obtaining a non O retirement from a visa exempt or tourist visa entry.

That is applied for 15 days + prior to expiry and has an under consideration period.

Here is thread from Nov last year.

https://aseannow.com/topic/1278429-travel-out-of-country-whilst-retirement-stamp-is-under-consideration/