The Duke series from Simpson is more densely packed than any of the other brushes and will give you that feel, as will the chubby.
If you were in the U.S., I'd just tell you to order Maggard's two-band brush. Since you are not, the most economical way is buy a knot from eBay. Ace Shaving on eBay sells fairly good quality knots.
Buy a brush handle that has an opening 2mm bigger than the knot size. Buy some two stage epoxy, mix it, coat the bottom of the hole, and part of the sides. Stick the knot in, give it a half twist and let dry for 24 hours.
The quality of Chinese made knots is not on the same level as hand tied knots from Simpsons, Thater, or Shavemac, but the performance and face feel will be the same. The difference will be in the shaping and the hair sorting before the knot is tied. Those companies will sort through the hair, picking out wispy, bent, and non-matching hair, whereas the Chinese don't do that great of a job, unless someone is willing to pay them to do so. That pre-sorting is time consuming, and is where the bulk of the cost of a brush comes from.
Making your own shave brush from a premade knot will save you £50-£100, and you should be able to make it for about £30. Or just buy one outright from ace shaving for a bit less.
http://www.ebay.co.uk/usr/aceshaving
Here is a big brush:
http://m.ebay.co.uk/itm/151248216704?_mwBanner=1
And a smaller 24mm "normal" size brush:
http://m.ebay.co.uk/itm/151041469678?_mwBanner=1