In message , Colin
Murphy writes

Unfortunately, I very rarely use the tube to travel and I have no
particular inclination to pay a tube journey surcharge just to use the
Auto top-up feature.

Is there any way to get around this?

According to the Oyster FAQ:

You will be sent an email when your Auto top-up instruction is
ready to be collected from your nominated station. If you do not
collect it within 8 days of being notified, the instruction will
be cancelled and your pay as you go top up will be refunded. You
will need to submit a new application to set up Auto top-up.

In other words, you will need to run-down the balance on your current
Oyster and then start afresh with a new one, preset to auto top-up.
Possibly the Oyster helpline can tell you if there is any quicker way to
do what you want.
--
Paul Terry