Yoggy,
I would recommend getting the best rod you can afford. You'll be holding it all day and mending the line, so something that is light is a top priority.
I feel a slim blank is of benefit as they slice through the air with less effort. This helps hit awkward bites and makes the process of mending the line easier.
Normally I would recommend a long rod to help with tackle control but because you're new to trotting I would go for a 14 footer if you can spend more than, say ?120, or a 13 footer if you can afford less. Those rods will be much easier to control.
Ideally a 17ft rod that handles like a 12 footer would be ideal, but if they exist I haven't seen them!
I would balance the power of the rod with the size of the fish you intend to catch.
If you're after Roach and Dace then go for a rod with the lightest line rating as you could easily end up using 1lb hooklengths. A softer rod really reduces hook pulls. Too many hook pulls and you'll spook the shoal. I prefer a spliced tip model, but they seem a rarity nowadays.
The problem with a rod like that is it would be hard pushed to keep decent sized Chub under control in pacy water, or pick up heavier line trotted at distance.
That's why I've got 4 different float rods!
I don't know which rods to suggest as I haven't been looking to buy for ages. Daiwa used be really good, especially the spliced to models. A mate of mine reckons the top end MAP rods are pretty good.
If there's a rod that is supposedly suited to 1lb to 3lb hooklengths, that should be better than going for a more all round tool. Many of the float rods nowadays seems suited to chucking wagglers at commercial Carp and as previously stated, these will be too heavy.
Hope that helps.