No worries.
Sorry to sound condescending but if money is tight and you want a high-end PC the sensible thing to do is save up. It's less agro.
If you can't wait but the £700 machine you posted is in budget then just go for that. Don't start worrying about this GPU or that one, because the GPU is literally the easiest part of the PC to swap in/out and buy/sell, so if you change your mind in 3 months it's no problem. (Not so with the motherboard/SSD/PSU etc. so it's worth getting them right first time IMO.)
Sorry to sound condescending but if money is tight and you want a high-end PC the sensible thing to do is save up. It's less agro.
If you can't wait but the £700 machine you posted is in budget then just go for that. Don't start worrying about this GPU or that one, because the GPU is literally the easiest part of the PC to swap in/out and buy/sell, so if you change your mind in 3 months it's no problem. (Not so with the motherboard/SSD/PSU etc. so it's worth getting them right first time IMO.)