75″ models that stand out when it comes to anti glare are going to sell for a lot more than £1000 I’m afraid. Even with that budget at 65″ I don’t think you’ll find something decent. If you wait until Black Friday £1000 would be a good budget to spend on the 55″ Samsung Q85T which will be very good at fighting glare. At 75″ though that TV costs a lot more.
If you could give us the model number of your existing TV it may help. If I was to take a guess your TV is going to be a lot better than what you can buy at 75″ today for 1k.