I went t a&e tonight they done blood tests to rule out blood clots etc. Wuld they have checked the bld test fr a stomach ulcer?

No blood test. There is no blood test for a stomach ulcer. Unfortunately, that is evaluated by endoscopy. Consult a gastroenterologist if persisting concerns.
Not usually. A blood test can tell you if you have been bleeding, which can be a sign of an ulcer, or it can tell you if you have an infection which causes an ulcer. Typically one needs an endoscopy (placing a thin lighted tube with a camera on it through your mouth into your stomach) to diagnose an ulcer.