How to spend £400 budget for bedroom set up

Bats_

I would suggest a Line 6 Catalyst, that will do everything on that list and allow you to use it as a power amp for any modeller. 

Buy a cheap, used V1 and update the firmware to V2. 

Ungulate

I have a Blackstar HT5R for sale, not advertised yet...

PFAllen2

Some good discounts on the Boss Katana Artist at Thomann as part of their 70th anniversary promotion.

mfin

L5-Studio 
(If you do all your metal stuff with pedals, it will do the blues thing very well, and takes pedals well)

WindmillGuitars

Katana Artist 1x12