Welcome to the forum. The difference will be that the T5 units are brighter, perhaps by up to 50% depending on reflectors. Brighter light automatically means higher probability of algae, faster growth rate, higher requirement to keep on top of CO2 and nutrients. For any beginner I would definitely suggest the T8 tubes, but other than the scientific implications, lighting is an emotional issue. Brighter tanks just look nicer when things are going well. The 50 quid will buy you more responsibility and headaches, but will also buy you an escape from the dreary winter days...
Well iam a very much a newbie this will be my first attempt at a fully planted tank so would you suggest i start off with the t8 and try out things like ferns mosses low light plants ect ?
Then possibly move on to more advance lighting, plants and co2 as i gain experience also if i dont use the co2 due to low lighting would liquid carbon be a good option also how would ricca grow in low light setup with liquid carbon
Well, I'd recommend that you start out with the T8s certainly, but that doesn't mean you have to limit your choice of plants. This is another issue which many beginners fail to recognize. The difficulty associated with "advanced" plants have nothing to do with light. It has to do with CO2. You need to worry 10X more about CO2, flow and distribution than you do about light. All plants, even the difficult ones will grow with the T8 bulbs you've specified, although they may not grow as fast and they may not color up in the same way but they will grow perfectly well.
You're welcome. Remember that just because you use lower lighting it does not mean that you should cancel any plans to use pressurized CO2. On average, for a given lighting level, injecting CO2 will generate growth rates 3X-5X higher than non-CO2 or even liquid carbon products. CO2 enrichment is valuable under any lighting condition, not just under high lighting. It's just that CO2 is more critical under high lighting. I don't see any reason to delay implementation of a pressurized system (if that was your original plan) and that's because you'll not be any better at injection techniques if you delay a year from now. It takes practice and so you might as well get started now. It all seems intimidating at first because there is so much to think about and so much equipment, but if you navigate to the Tutorial section of the forum you'll find lots of information there to keep you occupied, informed and hopefully, to keep you interested.
By the way, Riccia absolutely HATES liquid carbon and typically melts into oblivion if doses with significant quantity of these products, so if you plan to keep this species you'll either have to go non-CO2 or pressurized.