I do a fair bit of "rolling" on the Middle/Upper Severn.
I find its a better summer method than in the winter.
I use mono, and wrap lead wire around the hook shank.
Using different hook patterns with longer and shorter shanks means you can increase and decrease the lead weight.
I find chest waders are a must for getting into some of the tighter spots along the bank.
I try to look for anywhere where the flow rate changes, slow to fast or fast to slow.
These tend to indicate features.
Weed beds are a great feature to role a bait through too.
Make sure your hook point is completely buried, so to avoid hooking up on the bottom.
Make sure you have a good bow in your line.
You should (even with mono) feel a "tinkling" on the line as the bait trips along the bottom.
If it gets snagged up dont pull too hard to try to release it. I normally just dip the rod top under water, which increases the pressure on the line and quite often pulls the bait out of the snag.
If it wont come free, wind up slowly to the bait and try to bounce it out.
Its rare to get completely snagged, but it dose happen.
Bites, IMO tend to be either "slack liners" where all the tension goes and you need to wind up quickly till you feel the fish then nail it hard.
Or you get a "sharp wrap" on the rod top, followed by a tightening of the line, again nail it hard.
Its a fantastic searching method, and it becomes easier the more you do it.
I'd recommend that you try it in the warmer months when the fish are more active and more willing to chase a bait.
Steve
www.caravanonthesevern.co.uk
www.midlandriveranglers.yuku.com