Does BMI have gate checking on their ERJs?
 

Can I gate check a carry-on on a BMI ERJ145 flight? Doesn't seem like the overhead bins can handle a roller bag. Any experience?

Yes you can, and it is a very useful service, but don't forget you're still bound by the cabin baggage limits that apply through security.

Incidentally you'll find this information and other useful bits in the Flying with bmi FAQ, which is listed in the sticky at the top of this forum. Here's a shortcut for you:
http://www.flyertalk.com/forum/showthread.php?t=738267

Yes, the slight nuance being that you check your bag at the bottom of the aircraft steps (rather than at the gate) and get it back at the end of the flight immediately on exiting the aircraft. You don't have to wait to recover it from the luggage carousel.

What it doesn't say in the sticky is that many of the UK airports are now allowing 1 piece of hand baggage and 1 personal item.

Correct. It doesn't propose to list policies of individual airports.