What type of tiles - ceramic or stone? Will cost diff amounts to lay as have to be treated differently. Is it wet or dry ufh? What area do you live in?
If yu post more info I can let you know from my copious research last year (had to get 45m2 limestone floor laid!)
We have wet UFH and limestone floor. Paid almost as much to have it laid as for the tiles!! You do have to be careful with ufh and make sure you get flexible adhesive, as the tiles will be subject to more movement than normal. You can get tiles off the internet, can't remember the websites now but can post later if you like. They will send you samples first so you can see if they're ok. As you're having a big area done, try & go for larger than average tiles. As long as the floor area is not too funny a shape this should make them cheaper to lay.