If you need good clean headroom and 30-50W, forget about class, which in any case influences tone less than other factors such as biasing system, NFB amount and valve type. In true class A, you'll struggle to get more than 20-30W.
For bluesy indie stuff, you could do worse than a Marshall Bluesbreaker type amp, or even the similar 50W JMP combos, as used by Paul Weller for instance. Marshalls can do superb cleans, despite what many people think. The JTM45/Bluesbreaker in particular is a superb clean sound. A head and cab gives more flexibility and the capacity to change speaker config, important to maximise volume when searching for headroom.
My customers Al and Ivor (see my website) have similar requirements to you and achieve it in different ways. Al uses a Martamp M45 head (JTM Type) with a 4x12, set up clean. Trust me, it's the best clean you've ever heard, as much Fender as Marshall. Ivor has a Matchless DC30 type 1x12 combo, which also does a great clean sound, with that lovely chimey EF86 thing.
Cheers! :)