I went straight from kits to AG, but nowadays I am doing more Partial/Mini Mash brews than AG cos it is much quicker and easier and makes beer I cannot distinguish from AG. You can use any grains you like, because the presence of base malt in the mash converts the starches in any grains that need mashing. You get the benefits of AG brewing with the convenience and speed of extract brewing; it is effectively an extract brew with some base malt added into a temperature controlled steep. I make 12 or 13 litres usually, in a 15 litre stock pot, with a muslin bag and a colander. You could add more extract and hops and top up in the FV to a make a larger batch. Here's a quick guide to a typical brew - you can vary the brew length, the strength, and the ratio of grain to extract, obviously:
1. Heat about 4 litres of water to 70*C. You need around 2.75 to 3 litres per kg of grain.
2. Place a muslin or voile bag into the pot.
3. Stir in 1.5 - 2kg of grains. Adjust temp if necessary with cold or boiling water to achieve temp between 65 and 70C. Or gently heat the pot, but stir to prevent scorching the grains. I rarely need to adjust tbh.
4. Cover pot and wrap in towels, jumper etc.
5. After about 30 mins of the mash, start heating another 4-6 litres to 75*C in a separate pan if you have one.
5. After 45 - 60 mins of the mash pull the bag and place on a colander on top of the pot to drain.
6. Either dunk the bag in the other pot of 75*C water for a while and stir, or pour the water carefully through the grains. Allow all the water to drain from the grains.
7. Top up to 10-15 litres. Bring the wort to a boil. Once boiling, add hops according to your recipe schedule.
8. You can add the extract before the boil starts, or towards the end of the boil, or after you switch the heat off. I am now waiting til after the heat goes off, stirring the DME in, which helps get the temperature down, and doesn't interrupt the boil, and then often adding steeping hops at 80*C.
9. Cool in the sink. This volume will cool to about 30*C in about 30 minutes if you keep the water cold.
10. Transfer to FV via a sieve, top up to required level, and pitch yeast.
I reach flameout in about 2 hours, and get about 24 x 500ml bottles of good quality ale. I make stronger ales with extra extract, and bottle those in around 36 x 330ml bottles.
I'll add pics and recipe ideas in due course.
You can use this method to make larger batches, by increasing the amount of extract added, doing a partial boil, and increasing the hops. The link below explains this, with instructions to make a 19 litre batch, and explains the general PM method in more detail. I find the 24 bottles or so that I get is enough, and I can do a full boil or close to a full boil, and have a high percentage of the fermentables from the grain.
Further reading:
http://beerandwinejournal.com/c-top-partial-mash/