I did this alot when I was using kits. A partial mash over a kit is one way you can improve your beer flavour. As the kit is already bittered, you don't have to work out your bittering hops. If you are adding any sort of bittering hops, be very careful of the high alphas. A small amount goes a long way and you will need to understand IBU's and use a calculator.
It is a great vehicle to add some flavour and aroma additions as these add minimal amounts of bittering.
Do make sure you boil your wort for sixty minutes. There are alot of complex reactions that occur during the boil. Small amounts of wort from specialty malts only need a 10 minute boil when only doing kits and bits.
Do not try and work out your efficiency. The combination of small amounts, cobbled together equipment and new brewer mean that extraction is only about 50%. Trying to stack your efficiency up against the ag brewers figures will make you feel foolish. It is all about getting some fresh malt flavours into your brews, not about efficiency.
Try and mash about 2 kg of base malt to replace your usual 1kg baggy. This can easily be sparged in any kitchen with a large pot and a bit of cheesecloth pegged over the saucepan.
Do taste every part of the process. At the start of the mash, it will be a bit floury and grainy. At the end, after the enzymes have done their fantastic work, the mash is sweet.
Be warned, mashing is addictive.