Nice cameras to convert to pinhole photography are the Agfa Clack for 6x9 cm or the Agfa Click for 6x6 cm negatives, in case you do not have a 6x9 enlarger. Available at car boot sales for peanuts.
Normal color negative films have a fantastic latitude so exposure is seldom a problem. That counts also for the black and white film XP2 from Ilford that can be developed in any streetcorner printshop like a color film. If you want to go to still larger formats, try Harman's direct positive paper and develop in normal paper developer. For that you need long exposures, because the speed is about a few asa in practice.