Hey French47, no one will laugh at you here mate. We have all had to go along the same steep learning curve that is modern aquarium lighting.
To best advise you it kind of depends what you want to achieve and how you intend setting your aquarium up, as well as which plants you want to grow. Some (like echinodorus, anubias, microsorum, and many stem plants) don't need intense light. Other plants do, like most of the carpeting plants in general, and some of the more delicate plants you will find.
Depending on the above, will depend on what lighting you need to go for. Some would undoubtedly advise you that with a 2 foot deep tank, Metal Halide lighting would be a great benefit. You can raise or lower it depending on how great the light intensity you need, and there are some cracking "used" deals to be had on Ebay (I believe I saw a Giesemann Infiniti unit on there which was quoted as being big enough for a 5 footer) for about £250.
Remember, you have a cracking size tank there, but you dont necessarily have to have full floodlit illumination in every corner. You could have more intense lighting centred or to one side, with lower lighting to the sides.... there are loads of possibilities.
LED is a good way to go also. I am not sure exactly on how deep LED's are now considered to be useful to. You would certainly be wanting something like the TMC 1000ND range (I have one of these and its fantastic). But for a 5 foot tank you would be looking at a LOT of money. You would need at least three units, which would set you back about £165 each ... thats the cheapest I just found) plus either three controllers at £60 or a multicontroller at £200+. The multicontrollers do come up for about £120 second had quite a lot though.... Each tile uses two "channels" of the 8 channel controller, so it can run up to four tiles (or eight aquabeam bars which are not as nice IMHO but others love them... I prefer things more compact, lol). Either way for TMC tile set up you would be looking at just under £700. You could always approach the retailers concerned and see if they will do a discount based on that spend I guess.
Another alternative would be a unit like the AI Sol or the Ecotech Radion. They will set you back about £500 (one comes with its own controller the other you buy separately but the light itself is a bit cheaper). You would need TWO of these for sure, so thats a grand...
The cheaper option would be to go for a T5 tube luminaire. A decent one for your tank would be about half to two thirds the cost of TMC tiles and controller.
I hope that helps. If you have any questions I would be happy to try and help a bit more.
PS. Remember... the more light you throw at a plant, the more CO2 it needs (thus probably meaning you need a full on CO2 setup) and the more fertiliser it needs (read the article on EI dosing. It can be found here...
http://www.ukaps.org/EI.htm
Its actually VERY easy and VERY cheap and again, I can tell you what you need to buy and what quantities to mix
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