Visa eligibility

Hello,

I'm wondering if someone could help with me confusion. I recently came back from china early to the uk and I've already got a flight from shanghai to Tokyo booked for November. I'm wondering if I'll be able to book a flight from uk to shanghai and take advantage of this 72-hour free transit to have a look around shanghai and then use the already booked flight to Tokyo.

I'm unsure if this will be ok due to them being separate flights rather than me having a lay over.

Any help would be appreciated - edie_shemilthotmail.co.uk

Thanks so much.