The newish Sri Lankan place on the High Street – see Trip Adviser, it’s the top-rated place in town – is excellent. Really interesting flavours, great service. For pub food, The Wheatsheaf in Old Glossop is good. Not sure how well suited for vegetarians, but good.
The Old Hall Inn in Chinley is fantastic though, 20 minutes drive from Glossop on the other side of Hayfield – sort of upmarket pub, but totally unpretentious, really welcoming, and brilliant food. Been there in soaking wet bike kit and they didn’t bat an eyelid while we dried our boots in front of the fire. Great place.
Also, further afield again: the Samuel Fox in Bradwell is good too. Small, friendly, unpretentious restaurant.
And the Thai Noodle bar on Glossop High Street is bloody brilliant. Not what the OP is looking for, but amazing Thai food, cooked by Thai people, served in takeaway boxes, can’t go wrong.
The Globe does great, budget-friendly vegan food and homely, home-brewed beer. Dead cheap, nice pub. They also do a mean fish finger sandwich and chips at the Oakwood.
Don’t bother with Va Bene near the station. Looks look a hair salon from the outside and is woefully overrated ime. Comedy stereotypical Italian waiters flirting hilariously with middle-aged housewives is the speciality of the house… 😉 Ruchi, the ‘posh’ Indian place was good when it first opened, but seems to have got a bit complacent recently and is a bit ordinary these days.