I'd personally advise 32" at 4K... 27" is a bit on the small side unless you're sitting very close. Also IPS would be advisable given your use case. VA always suffers from obvious gamma shift.
The problem is, at your budget, there isn't really anything. The closest would be the BenQ PD3200U at £630.
On the VA front, there is the LG UHD 32UL500-W which can be had for £428. Not bad as VA goes. I'd still prefer IPS though, for your use case. There really is no reason to go with VA... it's a disadvantage in all aspects really.