I've lived in Gloucester for 35 years, yes there are rough areas like most places you just need to know where to avoid (and it's obvious when you drive past!
Avoid Barton, Tredworth, matson, coney hill, any of he "leazes" in longlevens, parts of kingsholm. And definitely avoid Gloucester park!!
The nice areas are tuffley, quedgeley, hucclecote, abbeymead, abbeydale, Hempstead and linden.
I've lived in Barton, tredworth, linden and quedgeley. There are good schools and churches in those areas.
For your budget housewise I would say you can get a 3 bed in linden easily, or tuffley.
I'm in linden area now and I love it