You've got a few options with temperature control, but definitely get a digital probe thermometer if you haven't already.
A lot of people mash in an insulted mash tun so that when the target temperature is reached, it will remain stable for the mash duration (in theory).
I brew in smaller batches so I can get away with heating a pot on the hob and holding it in the oven to maintain temperature. For bigger mashes a lot of people use hot water (known as "strike water") to attain the target temperature immediately... I think you'll find online calculators for strike water temps, but usually you're looking at 5+ degrees C above your mash temperature, since the grains take away some of the heat. If the insulation isn't too great you may need to add strike water during the mash to bring the temp back up. Be real careful if you want to heat on a plate/burner because if you don't stir fast enough it'll burn to the bottom of the tun... strike water is easier for even heating.
You'll find plenty of tutorials on youtube on making an insulated mash tun if that's the way you want to go. Overall, I think there's a reasonable initial investment in AG brewing but once you have your routine down it's not a difficult process! And the beer is lovely :wink:
