the 01:00 from exeter is most likely the sleeper and doesnt really have a fixed route from Taunton it can go via Westbury or Bristol to Swindon/Reading.
I have never been on it via Bristol has anyone here? the only time i did it it went via Westbury & Melksham to Swindon before proceding to Reading.
I've often been on the Sleeper and gone via Bristol
TM▸ , I've know passengers to board at Bristol rather than wait till the 04.xx train.
But then it doesn't always go via Bristol, it has a wide range of variations of route between Taunton & Reading., even more on a Sunday night between Exeter St D & Reading.