For the tones you describe, I'd go for a Laney GH50L head. As long as you don't need a sparkiling clean tone for gigging, they're a superb amp for very, very little money. I sold mine a while back for £250 which is what they seem to go for. Even brand new they're just under £400.
I'd go for:
Used GH50L = £250
Used 1936 Marshall 2x12 = £175
Total = £425
Then after a few gigs, or when you get a few quid, I'd swap the speakers in the 2x12 from the standard G12T-75s to something a bit warmer. I'd recommend Celestion Vintage 30s, G12H30s or G12-65s.