Check out Vapemate. I was skeptical at first but the liquid they have is great. Even my local B&M said she thought it was good stuff. You have a choice of flavours that is huge and can choose your ratio. Add in an extra flavour shot and I got my 30 ml for under 10 pounds including shipping.
The shipping is good too as the free shipping ships first class in 24 hours so is basically a 48 hour delivery if you order on a Monday.
And no. I'm not being paid to write this.
Another vendor for good flavours is Vampire Vape but they have a few
tank crackers in their line. Heisenberg is great. So is Pinkman. They were my ADV till I got a 30 ml from Vapemate.