Approx taxes to upgrade

Hi does anyone know approx taxes amount to upgrade economy to PE lhr-bom? I can see it’s 15,000 points but wondering on the taxes amount. Husband is flying with work who will only pay for economy flight, so thinking we could upgrade him with points as we have plenty but not if it’s loads of ££! Thanks!

Rough figure will be the difference between a PE and Economy booking.

It will be at least £ 100 to account for the difference in APD between economy and PE.

It’s showing £185 for the outbound and £80 if they’d like the return. So return total is ~£265

Amazing thank you both!