For ^15.75 Advance Purchase each way (I'm assuming 1 adult 1 child F&F) you can go 1st class on the FGW▸ 0913 from Bristol TM▸ to Exeter SD and return on the FGW 2044 from EXD» -BRI» . Then ^3.25 for an Off Peak Day Return from EXD-Dawlish. Does mean a unit from EXD though. Tis only 15 mins though.
Total ^34.75. With better comfort levels on the legs to/from Exeter, complimentary refreshments, served at seat in the morning, collect from buffet in the evening.
F&F railcard not valid for 1st class tickets
AFAIK▸ ?