The problem with the Trump offer - or rather the UK response to it - was timing. Technically the UK can’t enter into trade deals independently of the EU until it’s no longer a member. May had really no choice but to respond as she did while she was still attempting to secure a cooperative EU approach to the exit negotiatons.
So you'll get to send your Land Rovers and Minis to us and we'll get to send our 787s to you.