£1500?! wowwww..
Tire will run you £40-£60 quid,
Suspension arms around £118.39 for both
Rear brakes probably need replacing and that's like £47.44, however, it may just be your brake drums which they usually cost around £30.54
Front are around £3-£9
Let's say worst case scenario for cost of parts, and let's say it's £151. £1349 in labour is mental. Or maybe not, maybe that's a normal figure...
If you're not into the mechanical side or wanting to learn how to do the changes yourself, find a friend who will / can and you could join them? If not, look for another garage and offer to purchase the parts and bring it in for them and see how much they'd just charge for labour.
I've taken the suspension arms out a few times, done the front and rear brakes, it's noting too difficult but you'll find yourself getting agitated quite quickly. (This is my first car i've ever worked on btw) This forum is full of a great amount of posts to help you, I can even link them to you if need be.
What evidence did they have on the fact your car had an oil leak? Does your car leak some oil when the engine is running?
Also 126k is a lot of miles, if you've always serviced it, then you shouldn't worry about it dying any time soon.