Thanks K... I hadn't given a lot of thought to the exchange rate, but I think I'd better start! I was going to buy some nice perfume too, while over there, but maybe I need to do a bit of price research first...
Yeah, the day before Brexit, the exchange rate was up to $1.5 to the £, but as soon as the result came in it went down to about $1.3 to the £ and hasn't recovered yet.
The MacBook Air with the spec I want is £1,240 in the UK and $1,499 in the UK. Before Brexit, $1,499 came out to £999, so it was £240 cheaper to buy in the US.
However, right now, $1,499 is about £1,120.. And PC World have an offer on at the moment to get 10% cashback from MacBooks, so actually I might be able to get the one I want here in the UK for £1,116.