I use Bridgwater Cattle market t/s quite often.
Good showers, friendly staff, guy always remembers my name when I book in,.and the girls in cafe very helpful, decent cafe, also adjacent to choice of 2 pubs, (but a tad expensive) or a short cheap taxi ride into town…for those who’s arses ain’t bolted to the seat on a night out. 
MSA 100 yds away for a Maccy D coffee in the morning if you want.