So they sold me the car knowing it was basically frucked? Surely they shouldn't have let me drive off in that especially with a toddler with me

I bought a car from a dealer 80 miles away from me last Thursday. They told me it had a fault with the thermostat but it wouldn't stop me driving it back and If I wanted to buy it that day I could get it fixed myself. I did got 20 miles down the road before having to have it towed the rest of the way. The next day I took it and got the thermostat housing replaced which stopped the problem until yesterday. Today I got told the head gasket has gone and it will cost £1500 to get it fixed. Do I have right for a refund or repair costs covered? I feel like I was misled at the seriousness of the issue and it's one problem after another! I would also like to know if I had to get it towed back would it be at my cosy or theirs? Thanks