To get started as a competition dancer the first stage is to learn to dance, generally in a general or medal class to acquire the basics of the dances that you will need for competition.
It is possible at the beginning stage to enter a Class Pupils Section of a competition, if your Teacher thinks that you are ready.
To do this it might be possible even without a regular partner, as Showbiz Studio endeavours to organize for clients to dance in a Best Lady or Best Man section to get them started. This type of event does not require you to purchase special clothes other than appropriate Ballroom footwear. On an ongoing basis you need a partner who is in the right age group, height and registered standard. Your teacher can advise you of the requirements for registered competition.
Competition dancers take private lessons according to their finances. A minimum would be one hour of instruction per week and appropriate unsupervised practise time. Couples undertaking a lesson normally split the cost of the lesson between them.