We shy away from getting mimic and wonderpus because we do not know enough about them or their populations in the wild. However the type of octopus you want depends on the size of your tank. I wouldn't go any smaller than a 55gal.
In a 94 liter(24 gallon) tank the only species you could go with is a dwarf species. There are two problems with keeping dwarfs. First is availability, they are usually available in the spring and winter time, because they are caught as by catch from the commercial shrimpers in the Florida Keys. I have purchased mine from Tom's Caribbean in the past, but it will be few months before he gets any. The second problem with them is that they are very sensitive to light and highly nocturnal. They will come out at night when the room is completely dark. In addition to the above the dwarfs are typically not as interactive as the larger species, Dwhatley has had some success playing with hers but she is some kind of octopus whisperer! I cant get mine to do anything but eat.
also i know they escape so i wos thinkind of grtting some plastic sheet and cutting it you the shape of my tank nice and snug would that be ok what about toys lego stuff like that my mate used to use a little jar with food in it so it had to inscrew the lid to get the food
Only Sisturus was particularly playful and his activity helped Medusa be more social but most of mine have been very shy (I will have to admit that I have been able to see my mercs more than most though).
Given your location, there may be other options (still likely nocturnal). Octopuses are not like other fish where you can order a specific species (with a couple of exceptions) and expect that is what will show up. Before you get too set on how to organize your tank, see if you can locate a source for a dwarf (the only size that will work in your tank) and ask where it will come from. Be aware that the venemous blue ring is a dwarf species and we have seen them shipped without being labeled. If a supplier tells you it comes from Australia.