Paul there are various grades of ally some more ductile than others, some require the bend to follow the grain and some are suited to machining (7005) rather than bending, if you try to bend these grades the ally crack's along the fold but as a good guide 3003 or 5052 grade is easy to work and has strength, if you ring any of the online suppliers they will advise or Google to read up on the different characteristics. Just for your reference if 3003 is machined it tears and is a pain to get a good machined surface finish.
I used these
https://www.themetalstore.co.uk/prod...luminium-sheet well packaged which i re-used in the build.
Good luck and i look forward to seeing how you tackle the interior, happy days ahead me thinks.