coldwater tank, plants, algae & lighting...

I have a four foot coldwater tank, which until a month or so ago had no
hood and no lights - it gets slanting sun in the afternoon, and the only
plant I had in there was creeping jenny, which I appreciate isn't an
aquatic plant, but has grown happily for me over about eight months.

A month or so ago I added dojo loaches, who are notorious jumpers, to
the tank, so I also added a hood & a light, and some anacharis - which
did quite well in an unlit tank for me last year until it got eaten...

The lighting is pretty inadequate for plants at the moment - I think
it's 38 watts (fluorescent) and the tank is about 46/47 US gallons, and
I've started to get a fuzz of green algae on the stones/shells/wood and
plants - and on the tank glass. I'm not fussed about it on the
furniture, but I don't like it on the glass or plants much.

I have an idea that I need to: put another bulb in and add more plants.
Would this be a good plan? Part of me thinks I would get more algae,
part of me thinks that with more light the plants would be able to
out-compete it. I also think that maybe frequent water changes for a few
weeks might help? Nitrates are somewhere between 12.5 & 25, I think
closer to 12.5 but the kit (Tetra) only has those two options.

If this is a good idea, are there any other coldwater plants suitable
for a beginner? I'm coping with a small (overstocked) tropical tank
fine, but I'm finding coldwater plant advice hard to get in the two
(very nice) LFS I go to

All advice very gratefully received...

--
sophie