For Micro Groms there are a few options. Membership can be; pay as you go (1 session at a time), monthly (4 sessions) or a 2 month block (8 sessions).
Pay as you go: £35pp
1 month (4 sessions) £80
2 months (8 sessions) £140
Spaces on Micro Groms are limited so by purchasing a block your child gets one of the limited spaces for that period.
It is entirely up to you whether you attend each session, but due to restricted spaces it would not affect the price of the membership.