Where can I get antibiotics on A Sunday as I have a uti ?

Just wait the 24 hours and go to a doctor today.

Better, try 5000 mg of Ascorbic acid daily for 5 days.  This will usually cure it.  Buy it a lot of stores.  

That's not likely to happen with out a prescription and if your doctor doesn't work on weekends. Call your doctor Monday morning, a medical clinic or urgent care. Usually I can get a prescription in the same day that I have a doctor's appointment at my medical clinic. These days (in my area) appointments are done over the phone. Tell your doctor you need an appointment asap, when they call you tell them what you need. They should send a prescription to a pharmacy in your area. Go to the pharmacy and pick it up.

What a stupid question, by the time you get an answer it will be the middle of next week?

You'll probably have to go to an Urgent care. They are a lot cheaper than an ER.

Teledoc

in fact, you can call them right now.

The mini-clinics in drug stores can give you the test and prescribe anti-biotics. 

They stick you in the arm. "Not up the Valley."  A Uti is bacterial infection so that is known what they need to kill that.

You can go to urgent care, or just wait till Monday. In the meantime, drink lots of water. 

Surely there's a clinic open somewhere or call A&E at the hospital and ask if they know. Google weekend doctors in your area.