It is rare for a 2lb roach to be a lucky capture in my opinion, so if someone wants to catch one then it really does have to be a very conscious decision and with that comes a heavy commitment. You can't just go after them two or three times a season and expect to get one. So, chasing such a fish is not everyone's cup of tea.
But if you desperately want to achieve that goal then the first thing you have to decide is whether it is any two pound roach, or a river two pounder. The latter being a considerably more challenging target primarily because of the combination of our deteriorating rivers (see the recent damning reports on deteriorating chalkstream fly life) and predation (predominantly cormorants).
If you want a river two pounder my advice would be to focus on the Hampshire stretches that have got keepers looking out for them. It's no coincidence that Britford holds a head of big roach with Stuart looking out for them! But the Test and Itchen also hold plenty of two pounders and if you are prepared to pay the money you can get access. Such a campaign needs to start in the summer. Spend time walking the stretch in low water and understand where the bars, deeper runs and drop offs are. Come winter look for a steady run or crease of walking pace. Big roach don't like rubbish coming at them and they don't like water moving about in different directions so steer clear of that nice eddy collecting old leaves and detritus. If you pull in weed or rubbish on your hook then move your cast or move your swim.
Start fishing seriously in November but the best time is after the second spell of severe frost and the second good flood. Then the weed should be gone. Fish maggots by all means (red if it's gin clear, white if there is a little colour) but most big roach like a lump of flake...
If you are going to quiver tip you will be wasting your time, in my opinion, if you don't have a soft enough tip. They have a great ability to bang a rod tip or stiff quivertip and not get hooked!
There are plenty of stillwaters now with two pound roach. You'll have to be prepared to compete with the carpers. This needs research and I would say, if you really want a two, don't waste time in places where you
think there might be a two - you need to fish where you
know they are there. Cold frosty days can be very good, hunting out the slightly deeper water and fishing maggot, flake or caster. However the most successful approach is the fixed maggot feeder acting as a bolt rig. Not very traditional but at least you can fish a cane rod if you want to (not so easy when you are quivertipping if you want to do so effectively).
In short, fish where you are certain they exist. Put every effort that you possibly can into your preparation; venue, swim, tackle and bait. Then you are just going to have to fish and fish and fish until you get one.
This isn't everyone's cup of tea to work that hard at it (and that's just fine). I don't have the time or inclination for this approach these days but I did once (and I did get a few big ones!)
Good luck to anyone who tries; there is no fish like a two pound roach! Oh and get a copy of Mark Wintle's two books, Mark Everard's books, John Bailey's Roach the Gentle Giants and John Searl's books (RIP Sir). After you've stared at the pages dripping with two and three pounders, you'll have all the inspiration you'll need!