you may also be able to access your ftb and/or pps advances if needed to get you the freezer - yeah, it means you're losing money from the payment for six months - but getting freezer and paying it back is easier than trying to save that amount each fortnight when you don't have access to the freezer for bulk cooking...
NILS is a good idea - not had a lot of experience with them, but have referred people in the past. it's generally for essential goods, so a freezer should be ok to qualify you
i honestly don't think mince is that cheap in terms of cuts of meat, unless you go really cheap hamburger mince - other cuts can be equally cheap, and just as versatile, if not more so - i'd suggest watching the specials, getting to know if there is a local place that does cheap meat (no idea if you're anywhere near a Tasman outlet), and aiming to buy or cook in bulk. we have freezer space, so save up and do a decent meat shop every couple of months. means we only have to buy essentials each week, so can get away with a big shop maybe once a month, and then just bread/milk/fresh fruit and veg every other week, so live on about $50 a week - the big shop is maybe $130 - and then we spend a decent amount on a variety of meat every couple of months. check the local butcher to see if they do weekly/fortnightly "packs" too - they tend to be ok value - and some will negotiate with you to change items of similar "per kilo" prices to get something you prefer if you don't like one particular cut
make the most of the slow cooker where you can. umm, make soup at the end of each week with leftover veg, make as much as you can from scratch (which i'm sure you do anyway!), shop on a full stomach, with snacks for the girls if you have to take them with you. another option that i know can be hard with kids, but if you have anyone that can stay with them after they are asleep, sometimes the best time to shop is late at night when meat has been priced down...
we sometimes struggle - i'm fine with doing a tight budget, because i've done it since i left home, but until DD was born, DH had never really lived on a budget - we went from 140k plus to dole levels over night, and he still sometimes forgets that we don't have a large disposable income. i'm working the minimum number of hours that i can so that i can be home with DH as much as possible through this cancer treatment, and adding treatment costs into the mix, it's left us back on a realy tight budget - without the freezer, we'd be screwed, cos we bulk cook on my pay week, then freeze and eat from the freezer the following week - so if advances or the NILS scheme can help, go for it.
oh, we tried aldi, but i wasn't overly impressed - it really didnt' work out any cheaper than doing home brand or watching for specials - and the things that had a decent saving for DH to take in the truck with him (fruit in jelly) he said were so disgusting he threw them out - so we just dont' bother now unless there is something particularly good value in the catalogue and then we go in (usually art supplies for presents!)