Check out Merlin's excellent valve wizard site for designing tube amps here.
How to design valve guitar amplifiers
Without going into your circuit too much at this stage, I will note that having 1k2 as a voltage divider for your heater elevation is not a good idea. You don't want nearly all the B+ going to ground at that point (which it most surely will do with that load. So I suggest you try aiming for a voltage divider that is going to give you a total load of at least 220k. (That way it will act as a decent bleeder resistance path for discharging your filter caps safely at power off as well).
Also, having only one 10uF filter cap after the rectifier will probably leave too much ripple on your power rail. I suggest you use a CRC or CLC filter there.