VAT is going up you can be definatly sure of that.
I would expect 21-22%. Reasoning is simple, there was a long period of 15% which created a slight hole which needs plugging. So to securely fill any hole the plug needs to be oversized.
The decrease was meant to encourage spending, although im not sure it helped quite as much as planned, other than for those buying new cars or building extensions etc. However it still reduced "income" for the government, so has created a short fall.
In the long term i honestly dont see it being all doom and gloom. Given all the recent back tracking and manifestos from all im not driven by parties, more by the people in positions of power and their intentions. In the short term I think the outcome will be good.