Its actually a lot more difficult to board a cruiser from a small boat - higher sides and all. Plus the cruiser had a deeper draft, so the boats have to go out further. And while they can take more men, that means longer stationary taunting the LW.
If had been necessary, the RN would have committed a battleship. That's what they do. As OTL worked out, it wasn't necessary. It actually would only have been a good idea if they had a juicy tank target and some form of spotting, which the Army probably wasn't in a position to do at the time.