Red, as much as people can give you some advice on here you are going to need to go up with a good instructor and sort this out, plus some hours.
There is much to do in a circuit, in around 6 minutes, climbs, climbing turn, level turn, S & L, descending turn, descending, and that is not even taking into consideration lookout, checks, radio calls and landing. It's a lot. So let your instructor do some of the work until you get the hang of it, like the radio.
Make sure your instructor has given you a really thorough circuit briefing of exactly what you will do at every stage of the circuit, and how you correct any issues. Learn your pre-landing checks off by heart, and don't rush them.
The circuit involves things you know (climbing/descending, S & L), but make sure you are told the spacing to look for. On landing, make sure your instructor gives you definite instructions on where to look and what to look for, but with your height it may be a different picture to your instructor.
You can slow things down by not doing too many things at once, such as climbing to circuit height before turning downwind if at all possible. Later on you can combine things together to bring the circuits in nice and tight. In fast aircraft it is pretty normal to put down a first stage of flap late downwind, abeam the landing threshold, but use whatever technique you have been taught.
The Toowoomba Aero Club is very good. I know it is a long way, but I did some flying there because I found them to be very clear and very helpful. The drive is cheaper than extra dual hours.
Do make sure you find an aircraft to fit you, I fly GA so can't comment on appropriately sized RA-Aus aircraft, people here may have some good ideas. In GA your weight would give more leeway for carrying fuel than with the low weight limit of RA-Aus, and Cessnas do seem to be made for the tall.