Once you get the NHS gastroenterologist appointment they can be very thorough, I had endoscopy, ultrasound, CT and MRI all within a few weeks. However, I had to wait 6 months for the first appointment as the waiting lists are so high for gastroenterology.
I was admitted twice by ambulance with a suspected bleeding ulcer but they refused an emergency endoscopy each time as they were just too overwhelmed.
My nausea was so strong that I lost 2 stone, and figured out by myself it was peri, during that wait but had the tests for reassurance (and they did find benign growths on my liver from high oestrogen) but was dismissed each GP and A&E appointment with “go home, stop worrying and eat something”.
Yes we shouldn’t have to seek private treatment but the reality is very differently unfortunately.