Are you joining pony club in the US? I am a graduate B pony clubber and now teach and examine through the C2 rating level. You are not required to braid for pony club and in fact are not allowed to until you are a C1 or above so you have 3 ratings to take before you are even allowed to briad. So you have plenty of time to practice :)
Pony club likes grooming over bathing although as you get higher rated you will need to bathe too but not as a substitute for grooming. As a new pony cluber the expectation is that your tack be clean and that your pony be well brushed. This means no dry mud of sweat, hooves picked out and tail and mane brushed through. There are no requirements on mane length or what side it should fall on so don't worry about that.
Let me know if you have any other questions or ask your clubs district commissioner. You're going to love Pony Club and will have a great time.