I'd go £1100 for the 256GB version, or cheaper for a 64GB version. There's no way I'm paying more than £1100 for a phone either, and I don't think Apple is going to release something as expensive as that. People call Apple for their prices, but they're always trying to minimise costs without minimising functionality / quality. I'd be surprised if we have an iPhone 8 that doesn't have a sub-£1000 price. I'm expecting £995 for 128GB at most - and I'd be surprised by that.
£895 would be believable and acceptable. £995 would be alarming. Post-£1000 and people won't be buying.