For MT, 31500-SV2-011HE
It's now £101 RRP. Used to be much cheaper than that.
12V 65AH
BCI 525, DIN 250 or uprated by now as the manufature/base model changes over the years and the technology advances.
CCA 520A (EN) or above.

aka 70D23L-MF for MT model.

Check with your local Honda garage for the delivery schedule.
Or, just pick up the equivalent from the above link.
If visiting Halford, look for Yuasa HSB005. Can't go wrong with Yuasa.

Kaz