Fine. I agree with upgrading the lighting. Floating plants are to me essential in any tank of forest fish, as I've frequently written.
Over a 30-inch tank you have three options. A single-tube T8, a dual tube T-8 or a single-tube T5. The "T" refers to the tube diameter in 8ths of an inch. But T5 and T8 tubes are not interchangeable, so it is either or, and tubes must be the same. T8 is the standard fluorescent lighting, probably what you now have. T5 is newer, and the tubes are HO (high output), meaning more light intensity. T5 are more expensive for fixtures and tubes.
A single T8 fixture with a 24-inch tube. I have this over my 30-inch 29g and it works fine for low and moderate light plants. Swords, crypts, Vallisneria, Anubias, Java Fern, Java Moss, Brazilian Pennywort--all these do well in this moderate light. And I have floating plants too. This is the bare minimum though; to go a step further as you've indicated, I would move to a T5.
My main choice would be a single T5 with a 24-inch tube. This is 1.5 times more light intensity than the same-length T8. But it would still be manageable, though you might have to lessen the photoperiod (duration) to prevent excess algae, depending upon the plants and extent of floating plants.
The dual T8 would be the most light intensity, and without CO2 diffusion and daily nutrient fertilization I would not suggest this much light over a relatively small tank. A dual T5 would be even more, better intended for marine reef setups.
I know you are in the UK, but I only know North American sites so I'll link one to give examples of the above; you should be able to find these fixtures in the UK.
Single tube T8 with 24-inch tube, this is a full hood and fixture: Aquarium Lighting & Hoods: All-Glass Deluxe Fluorescent Full Hoods - Black
This is a fixture only, requiring a glass cover under the fixture: Fluorescent Aquarium Lighting: Perfecto Fluorescent Single Strip Lights
Single tube T5 HO. This is a 24-inch fixture but the arms expand and it will fit up to a 36-inch tank length. Also needs a glass cover under it. Aquarium Lighting for Planted & Reef Aquariums: Hagen GLO T5 HO Linear Fluorescent Fixtures
For tubes for any of these, I recommend Life-Glo. ZoomMed (if available in UK, probably) also make one called Ultra Sun that is much the same and slightly less expensive. Again, T8 fit T8 fixtures, T5 HO fit T5 fixture. There is a link on the above pages to a page with the tubes listed.